List message threads

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

Annotations already provide readOnlyHint=true, destructiveHint=false, and openWorldHint=true. The description adds behavioral context by specifying the output fields (who, subject, last-message preview, unread state) and that it's a list of DM threads. This goes beyond what annotations convey, earning a 4.

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, front-loaded sentence that clearly communicates the resource and key attributes. No wasted words, perfectly concise.

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 (one optional param, no required params, output schema present, annotations present), the description is sufficient. It conveys the purpose, scope, and output content, making it complete for an agent to use correctly.

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 only parameter 'page' is fully described in the schema (page number, 1-based). The tool description does not add additional parameter semantics beyond what the schema already provides, so the baseline 3 applies.

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 tool's function: listing direct-message threads with specific fields (who, subject, last-message preview, unread state). It distinguishes itself from siblings like get_conversation (which likely retrieves a single thread) and other list_* tools by specifying DM threads.

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 context for when to use this tool (to get an overview of DM threads) but doesn't explicitly mention alternatives or exclusions. Given the sibling tools, it's implied that get_conversation is for individual thread detail, but this isn't stated explicitly.

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