list_thread_attachments

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

Without annotations, the description must fully disclose behavior. It correctly notes that it returns metadata only (no bytes) and is cheap. However, it doesn't mention any prerequisites beyond having a connected account (implied by param description), potential errors, or what happens if thread has no attachments. It lacks details on idempotency or side effects.

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 extremely concise, using two short sentences to convey core purpose, output fields, behavioral note (cheap, no bytes), and alternative tool. Every word earns its place. It is well-structured and easy to parse.

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 straightforward list tool with two parameters and no output schema, the description covers the essential aspects: what it lists, what fields are returned, that it's cheap (no bytes), and how to fetch actual attachments. It lacks details on error handling, account scope requirements, and potential limits on number of attachments, but these are minor gaps.

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?

The input schema includes two required parameters, but only account has a description (in schema). The tool description does not elaborate on the parameters or their formats. thread_id lacks any description, and the tool description does not provide guidance on valid values or how to obtain them. Given the 50% coverage in schema and no additional help in description, parameter semantics are insufficient.

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 states the verb (list), resource (metadata for all attachments in a thread), and scope (all attachments, not bytes). It distinguishes from the sibling get_attachment by noting that this returns metadata only and is cheap.

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 clear guidance on when to use this tool (to list attachment metadata) and when to use the alternative get_attachment (to fetch one attachment's bytes). It does not mention other potential uses or exclusions beyond that, but the context is sufficient for differentiating from the most relevant sibling.

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