MCP API glossary
What MCP tool annotations tell clients about a tool. Select an annotation or full API badge to open its definition here.
The signature and entry documentation describe the API’s behavior, including its calling conventions, storage and runtime checks.
MCP tool annotations#
These are server-supplied hints, not enforced guarantees. Clients must not base tool-use decisions on annotations from untrusted servers.
readOnlyHint#
True indicates that the tool leaves its environment unchanged.
Defaults to false when omitted.
References: MCP ToolAnnotations .
destructiveHint#
True indicates potentially destructive changes; false indicates additive changes only.
Defaults to true. Meaningful only when readOnlyHint is false.
References: MCP ToolAnnotations .
idempotentHint#
True indicates that repeating a call with identical arguments adds no further effects.
Defaults to false. Meaningful only when readOnlyHint is false. It does not promise identical responses.
References: MCP ToolAnnotations .
openWorldHint#
True indicates possible interaction with external entities; false indicates a closed interaction domain.
Defaults to true. This describes the interaction domain, not whether the tool writes data.
References: MCP ToolAnnotations .
title#
A display title for the tool.
The tool’s top-level title takes precedence, followed by annotations.title, then name.
References: MCP ToolAnnotations .
Symbol kinds#
Kinds identify declarations in the Python API reference.
class#
A Python type defining attributes and behavior for its instances.
References: Python classes .
function#
A Python callable defined with def or a lambda expression.
References: Python function definitions .
method#
A Python callable obtained through a class or instance. An ordinary bound method supplies its instance as the first argument.
References: Python instance methods .
property#
A Python descriptor whose getter, setter or deleter runs during attribute access.
A property need not correspond to a stored field, and reading it may execute code.
References: Python properties .
attribute#
A named Python value accessed on an object or class, potentially through a descriptor or dynamic lookup.
References: Python attribute access .
constant#
A named Python API value conventionally treated as constant. Uppercase naming does not prevent reassignment at runtime.
References: Python constant naming .
exception#
A Python exception class whose instances can be raised and handled with except.
References: Python exceptions .
Modifiers#
Modifiers add information about calling, implementing, or accessing a declaration. Their precise effect follows the language and the signature.
classmethod#
A Python method that receives the class as its implicit first argument, including when called through an instance.
References: Python class methods .
async#
A Python coroutine function declared with async def. Calling it creates a coroutine to await or schedule.
References: Python coroutine functions .
inherited#
A Python member resolved from a base class through the method resolution order.
The reference names the declaring class so its original definition remains navigable.
References: Python inheritance .
Package context#
Package labels identify where an API is supplied.
package#
The Python distribution supplying this API. Its installation name can differ from the package name used in imports.
References: Python distributions and import packages .