Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?

Annotations already establish readOnlyHint=false, destructiveHint=false, and idempotentHint=false, so the description is not required to repeat those. It adds valuable behavioral context beyond the annotations: the operation fails with specific error categories (not found, not the author, or validation) and returns the updated post. This is meaningful and non-redundant.

Agents need to know what a tool does to the world before calling it. Descriptions should go beyond structured annotations to explain consequences.

Is the description appropriately sized, front-loaded, and free of redundancy?

The description is compact and front-loaded with the core purpose. Each parameter is given a one-line treatment, and the return behavior is specified in two short lines. Every sentence carries information; there is no filler or repetition of schema fields.

Shorter descriptions cost fewer tokens and are easier for agents to parse. Every sentence should earn its place.

Given the tool's complexity, does the description cover enough for an agent to succeed on first attempt?

For a three-parameter mutation with no output schema and no enums, the description is nearly complete: it covers purpose, constraints, format requirements, error behavior, and return shape. It could additionally note that all three parameters are required and that the operation overwrites existing title/content, but these are minor gaps given the schema's required list and the description's already strong coverage.

Complex tools with many parameters or behaviors need more documentation. Simple tools need less. This dimension scales expectations accordingly.

Does the description clarify parameter syntax, constraints, interactions, or defaults beyond what the schema provides?

Schema description coverage is 0%, so the description must compensate, and it does. It adds critical validation constraints absent from the schema: title must be 3-200 chars and content must be 10-10000 chars. It also clarifies that post_id is the target to update and content is raw markdown. This goes well beyond the bare schema property names.

Input schemas describe structure but not intent. Descriptions should explain non-obvious parameter relationships and valid value ranges.

Does the description clearly state what the tool does and how it differs from similar tools?

The description states a specific verb ('Update'), a resource ('forum post'), and a key scope constraint ('author only'). It is clearly distinguishable from siblings like create_forum_post and delete_forum_post, and the leading phrase leaves no ambiguity about what the tool does.

Agents choose between tools based on descriptions. A clear purpose with a specific verb and resource helps agents select the right tool.

Does the description explain when to use this tool, when not to, or what alternatives exist?

The description clearly implies when to use the tool: to modify an existing forum post the user authored. It does not explicitly name sibling alternatives or state when not to use it (e.g., 'use create_forum_post to create a new post'), but the 'author only' constraint provides strong practical guidance and excludes common misuse cases.

Agents often have multiple tools that could apply. Explicit usage guidance like "use X instead of Y when Z" prevents misuse.