list_attachments

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

No annotations provided, so description carries full burden. It explains that only explicitly downloaded attachments are listed, not those unfetched. It also specifies return fields. However, it does not explicitly state that the operation is read-only, though implied. No contradictions with annotations (none exist).

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?

Three sentences, front-loaded with purpose. Each sentence adds value: purpose, return details, usage guidance. No wasted words.

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 no parameters and no output schema, description is complete: explains purpose, return contents, and usage context. Covers what an agent needs to decide when to call it and what to expect.

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?

Input schema has no parameters (100% coverage trivially). Description adds meaning by explaining what the tool returns and the condition for listing (downloaded only). Baseline for 0 params is 4, and description meets it well.

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?

Description clearly states 'List all Signal attachments that have been downloaded and saved to the local store' with a specific verb and resource. It distinguishes from siblings like get_attachment (retrieves file content) and receive_messages (downloads new attachments).

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?

Explicitly states when to use ('discover what media files are available locally before reading them') and when not to use ('Do NOT use to download new attachments from Signal servers — use receive_messages for that'). Also clarifies that only downloaded attachments appear.

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