Get Mail Thread

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

No annotations are provided, so the description carries the full burden. It discloses the core behavior (fetching a thread by ID) but does not elaborate on any side effects, authentication requirements, rate limits, or response characteristics. For a simple fetch, this is adequate but minimal.

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 a single sentence that efficiently communicates the tool's purpose and key usage hint. There is no redundancy, and the most important information is front-loaded.

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?

Given the tool's simplicity (2 parameters, no output schema), the description covers the essential aspects: what it fetches and how to obtain the required ID. It does not describe the return value, but for a straightforward fetch the agent can infer that. A complete description might add output details, but it is not severely lacking.

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?

With 100% schema description coverage, the baseline is 3. The description adds value by explaining that threadId values come from search_mail results, which provides practical context beyond the schema's definitions. This slight improvement raises the score to 4.

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 clearly specifies the action ('Fetch'), the resource (Gmail thread or Microsoft 365 conversation), and the identifier types (threadId/conversationId). It also distinguishes this tool from siblings by noting that IDs come from search_mail results.

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 provides explicit guidance on when to use this tool: after search_mail, since it says 'Use ids from search_mail results.' This implies the prerequisite step. However, it does not explicitly name alternatives or state when not to use this tool, though the context is clear.

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