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

Annotations already declare readOnlyHint and idempotentHint, and the description adds behavioral details beyond those: it translates statuses (submitted/converting → preparing, etc.) and explicitly instructs not to dump raw status timelines or internals. This is valuable context not covered by annotations. The side-effect note is consistent with the annotations.

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 concise and front-loaded, leading with the primary purpose, then adding behavioral notes. Every sentence earns its place, with no filler or redundancy.

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?

The description covers the tool's function, status handling, and read-only safety. It does not mention pagination, output format, or error handling, but an output schema exists to cover return structure. For a read-only list tool with one optional parameter, this is adequately complete.

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 single parameter user_id is fully documented in the schema (including a default value), and the description adds no additional parameter-specific information. With 100% schema coverage, the baseline 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?

The description states the tool lists outbox faxes that are waiting to be sent, a specific verb+resource with a clear condition. This distinguishes it from list-faxes and other fax-related tools. It also mentions status translation, further clarifying the tool's function.

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 clearly implies when to use this tool (to view pending outbound faxes) but does not explicitly mention alternatives or exclusions. It provides enough context for an agent to infer the appropriate scenario, though it stops short of naming sibling tools or stating when not to use it.

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