List Threads

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

Annotations already indicate readOnlyHint and openWorldHint. Description adds valuable context: email content and metadata are untrusted, and each row's id is for fetching via get_thread. No contradictions. Good, but could mention ordering or pagination details.

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?

Two sentences: first states action, second gives critical usage context. No fluff, front-loaded, every sentence earns its place.

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 output schema exists, description need not detail return values. It covers purpose, usage of id, and security warning. Could mention default sort or limitation to summaries, but fairly complete for a list tool.

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 3 parameters with full description coverage (100%). Description does not add extra parameter details beyond what schema provides. Baseline score of 3 is appropriate.

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 verb 'list' and resource 'thread summaries in a mailbox'. It distinguishes from siblings like shipmail_get_thread and shipmail_list_messages by explaining the relation to get_thread. Also adds note about untrusted data, which is specific.

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?

Gives guidance to use the id from rows with shipmail_get_thread and warns about untrusted external data. Could be more explicit about when to use vs alternatives like shipmail_list_messages, but overall clear context.

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