pydantic_ai.native_tools
NATIVE_TOOL_TYPES
module-attribute
NATIVE_TOOL_TYPES: dict[str, type[AbstractNativeTool]] = {}
Registry of all native tool types, keyed by their kind string.
This dict is populated automatically via __init_subclass__ when tool classes are defined.
ImageAspectRatio
module-attribute
ImageAspectRatio = Literal[
"21:9",
"16:9",
"4:3",
"3:2",
"1:1",
"9:16",
"3:4",
"2:3",
"5:4",
"4:5",
]
Supported aspect ratios for image generation tools.
ImageGenerationModelName
module-attribute
ImageGenerationModelName = (
Literal[
"gpt-image-2",
"gpt-image-1.5",
"gpt-image-1",
"gpt-image-1-mini",
]
| str
)
Known OpenAI image generation model names, or another OpenAI image model ID.
AbstractNativeTool
dataclass
Bases: ABC
A native tool that can be used by an agent.
This class is abstract and cannot be instantiated directly.
The native tools are passed to the model as part of the ModelRequestParameters.
Source code in pydantic_ai_slim/pydantic_ai/native_tools/__init__.py
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kind
class-attribute
instance-attribute
kind: str = 'unknown_native_tool'
Native tool identifier, this should be available on all native tools as a discriminator.
optional
class-attribute
instance-attribute
optional: bool = False
Whether this instance is a best-effort upgrade rather than a hard requirement.
When True, the instance is silently dropped from the request on a model that doesn't
support it natively, instead of raising when no local fallback is provided. Use for
native tools where a fallback path exists (e.g. a local function tool that takes over when
the native one isn't available). When False (the default), the request errors on
models that can't honor the native tool — the user explicitly asked for it, so fail loudly
rather than silently substituting different behavior.
unique_id
property
unique_id: str
A unique identifier for the native tool.
If multiple instances of the same native tool can be passed to the model, subclasses should override this property to allow them to be distinguished.
label
property
label: str
Human-readable label for UI display.
Subclasses should override this to provide a meaningful label.
WebSearchTool
dataclass
Bases: AbstractNativeTool
A native tool that allows your agent to search the web for information.
The parameters that PydanticAI passes depend on the model, as some parameters may not be supported by certain models.
Supported by:
- Anthropic
- OpenAI Responses
- Groq
- xAI
- OpenRouter
Source code in pydantic_ai_slim/pydantic_ai/native_tools/__init__.py
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search_context_size
class-attribute
instance-attribute
search_context_size: Literal["low", "medium", "high"] = (
"medium"
)
The search_context_size parameter controls how much context is retrieved from the web to help the tool formulate a response.
Supported by:
- OpenAI Responses
- OpenRouter
user_location
class-attribute
instance-attribute
user_location: WebSearchUserLocation | None = None
The user_location parameter allows you to localize search results based on a user's location.
Supported by:
- Anthropic
- OpenAI Responses
blocked_domains
class-attribute
instance-attribute
If provided, these domains will never appear in results.
With Anthropic, you can only use one of blocked_domains or allowed_domains, not both.
Supported by:
allowed_domains
class-attribute
instance-attribute
If provided, only these domains will be included in results.
With Anthropic, you can only use one of blocked_domains or allowed_domains, not both.
Supported by:
- Anthropic, see https://docs.anthropic.com/en/docs/build-with-claude/tool-use/web-search-tool#domain-filtering
- Groq, see https://console.groq.com/docs/agentic-tooling#search-settings
- OpenAI Responses, see https://platform.openai.com/docs/guides/tools-web-search
- xAI, see https://docs.x.ai/docs/guides/tools/search-tools#web-search-parameters
max_uses
class-attribute
instance-attribute
max_uses: int | None = None
If provided, the tool will stop searching the web after the given number of uses.
Supported by:
- Anthropic
WebSearchUserLocation
Bases: TypedDict
Allows you to localize search results based on a user's location.
Supported by:
- Anthropic
- OpenAI Responses
Source code in pydantic_ai_slim/pydantic_ai/native_tools/__init__.py
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country
instance-attribute
country: str
The country where the user is located. For OpenAI, this must be a 2-letter country code (e.g., 'US', 'GB').
XSearchTool
dataclass
Bases: AbstractNativeTool
A native tool that allows your agent to search X/Twitter for posts and content.
This tool is exclusive to xAI models. See https://docs.x.ai/developers/tools/x-search for more details.
Supported by:
- xAI
Source code in pydantic_ai_slim/pydantic_ai/native_tools/__init__.py
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allowed_x_handles
class-attribute
instance-attribute
If provided, only posts from these X handles will be included (max 10).
Supported by:
excluded_x_handles
class-attribute
instance-attribute
If provided, posts from these X handles will be excluded (max 10).
Supported by:
from_date
class-attribute
instance-attribute
from_date: datetime | None = None
If provided, only posts created on or after this datetime will be included.
Naive datetimes are interpreted as UTC by the xAI API.
Supported by:
to_date
class-attribute
instance-attribute
to_date: datetime | None = None
If provided, only posts created on or before this datetime will be included.
Naive datetimes are interpreted as UTC by the xAI API.
Supported by:
enable_image_understanding
class-attribute
instance-attribute
enable_image_understanding: bool = False
Enable image analysis from X posts.
Supported by:
enable_video_understanding
class-attribute
instance-attribute
enable_video_understanding: bool = False
Enable video analysis from X content.
Supported by:
include_output
class-attribute
instance-attribute
include_output: bool = False
Include raw X search results in the response as
NativeToolReturnPart.
Without this, the model uses the search results internally but only returns its text summary. Enabling it gives programmatic access to searched posts, sources, and metadata.
Can also be set via
XaiModelSettings.xai_include_x_search_output.
Supported by:
CodeExecutionTool
dataclass
Bases: AbstractNativeTool
A native tool that allows your agent to execute code.
Supported by:
- Anthropic
- OpenAI Responses
- Bedrock (Nova2.0)
- xAI
Source code in pydantic_ai_slim/pydantic_ai/native_tools/__init__.py
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WebFetchTool
dataclass
Bases: AbstractNativeTool
Allows your agent to access contents from URLs.
The parameters that PydanticAI passes depend on the model, as some parameters may not be supported by certain models.
Supported by:
- Anthropic
Source code in pydantic_ai_slim/pydantic_ai/native_tools/__init__.py
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max_uses
class-attribute
instance-attribute
max_uses: int | None = None
If provided, the tool will stop fetching URLs after the given number of uses.
Supported by:
- Anthropic
allowed_domains
class-attribute
instance-attribute
If provided, only these domains will be fetched.
With Anthropic, you can only use one of blocked_domains or allowed_domains, not both.
Supported by:
blocked_domains
class-attribute
instance-attribute
If provided, these domains will never be fetched.
With Anthropic, you can only use one of blocked_domains or allowed_domains, not both.
Supported by:
enable_citations
class-attribute
instance-attribute
enable_citations: bool = False
If True, enables citations for fetched content.
Supported by:
- Anthropic
max_content_tokens
class-attribute
instance-attribute
max_content_tokens: int | None = None
Maximum content length in tokens for fetched content.
Supported by:
- Anthropic
ImageGenerationTool
dataclass
Bases: AbstractNativeTool
A native tool that allows your agent to generate images.
Supported by:
- OpenAI Responses
Source code in pydantic_ai_slim/pydantic_ai/native_tools/__init__.py
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action
class-attribute
instance-attribute
action: Literal['generate', 'edit', 'auto'] = 'auto'
Whether to generate a new image or edit an existing image.
Supported by:
- OpenAI Responses. Default: 'auto'.
background
class-attribute
instance-attribute
background: Literal["transparent", "opaque", "auto"] = (
"auto"
)
Background type for the generated image.
Supported by:
- OpenAI Responses. 'transparent' is only supported for 'png' and 'webp' output formats.
input_fidelity
class-attribute
instance-attribute
input_fidelity: Literal['high', 'low'] | None = None
Control how much effort the model will exert to match the style and features, especially facial features, of input images.
Supported by:
- OpenAI Responses. Default: 'low'.
moderation
class-attribute
instance-attribute
moderation: Literal['auto', 'low'] = 'auto'
Moderation level for the generated image.
Supported by:
- OpenAI Responses
model
class-attribute
instance-attribute
model: ImageGenerationModelName | None = None
The image generation model to use.
Supported by:
- OpenAI Responses. Defaults to the provider's image generation model selection.
Known image generation models include
gpt-image-2,gpt-image-1.5,gpt-image-1, andgpt-image-1-mini.
This selects the underlying image generation model used by the tool; it does not change the agent's conversational model.
output_compression
class-attribute
instance-attribute
output_compression: int | None = None
Compression level for the output image.
Supported by:
- OpenAI Responses. Only supported for 'jpeg' and 'webp' output formats. Default: 100.
- Google (Vertex AI only). Only supported for 'jpeg' output format. Default: 75.
Setting this will default
output_formatto 'jpeg' if not specified.
output_format
class-attribute
instance-attribute
output_format: Literal['png', 'webp', 'jpeg'] | None = None
The output format of the generated image.
Supported by:
- OpenAI Responses. Default: 'png'.
- Google (Vertex AI only). Default: 'png', or 'jpeg' if
output_compressionis set.
partial_images
class-attribute
instance-attribute
partial_images: int = 0
Number of partial images to generate in streaming mode.
Supported by:
- OpenAI Responses. Supports 0 to 3.
quality
class-attribute
instance-attribute
quality: Literal['low', 'medium', 'high', 'auto'] = 'auto'
The quality of the generated image.
Supported by:
- OpenAI Responses
size
class-attribute
instance-attribute
size: (
Literal[
"auto",
"1024x1024",
"1024x1536",
"1536x1024",
"512",
"1K",
"2K",
"4K",
]
| None
) = None
The size of the generated image.
- OpenAI Responses: 'auto' (default: model selects the size based on the prompt), '1024x1024', '1024x1536', '1536x1024'
- Google (Gemini 3 Pro Image and later): '512' (Gemini 3.1 Flash Image only), '1K' (default), '2K', '4K'
aspect_ratio
class-attribute
instance-attribute
aspect_ratio: ImageAspectRatio | None = None
The aspect ratio to use for generated images.
Supported by:
- Google image-generation models (Gemini)
- OpenAI Responses (maps '1:1', '2:3', and '3:2' to supported sizes)
MemoryTool
dataclass
Bases: AbstractNativeTool
A native tool that allows your agent to use memory.
Supported by:
- Anthropic
Source code in pydantic_ai_slim/pydantic_ai/native_tools/__init__.py
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MCPServerTool
dataclass
Bases: AbstractNativeTool
A native tool that allows your agent to use MCP servers.
Supported by:
- OpenAI Responses
- Anthropic
- xAI
Source code in pydantic_ai_slim/pydantic_ai/native_tools/__init__.py
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url
instance-attribute
url: str
The URL of the MCP server to use.
For OpenAI Responses, it is possible to use connector_id by providing it as x-openai-connector:<connector_id>.
authorization_token
class-attribute
instance-attribute
authorization_token: str | None = None
Authorization header to use when making requests to the MCP server.
Supported by:
- OpenAI Responses
- Anthropic
- xAI
description
class-attribute
instance-attribute
description: str | None = None
A description of the MCP server.
Supported by:
- OpenAI Responses
- xAI
allowed_tools
class-attribute
instance-attribute
A list of tools that the MCP server can use.
Supported by:
- OpenAI Responses
- Anthropic
- xAI
FileSearchTool
dataclass
Bases: AbstractNativeTool
A native tool that allows your agent to search through uploaded files using vector search.
This tool provides a fully managed Retrieval-Augmented Generation (RAG) system that handles file storage, chunking, embedding generation, and context injection into prompts.
Supported by:
- OpenAI Responses
- Google (Gemini)
- xAI (mapped to collections search)
Source code in pydantic_ai_slim/pydantic_ai/native_tools/__init__.py
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file_store_ids
instance-attribute
The file store IDs to search through.
For OpenAI, these are the IDs of vector stores created via the OpenAI API. For Google, these are file search store names that have been uploaded and processed via the Gemini Files API. For xAI, these are collection IDs for the xAI collections search tool.
SUPPORTED_NATIVE_TOOLS
module-attribute
SUPPORTED_NATIVE_TOOLS = frozenset(values())
Set of all native tool types.