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

The description adds meaningful behavior beyond annotations: it instructs the agent to translate statuses into user-friendly categories and explicitly warns against dumping raw status timelines or internals. It also confirms read-only behavior, consistent with the readOnlyHint and destructiveHint annotations. This is useful operational context.

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 short and front-loaded, with the core action and scope stated first. The 'Side effects: none (read-only)' sentence is redundant with the annotations but not harmful. Each other sentence earns its place, particularly the status-translation guidance.

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 simple read-only list operation with an optional, fully documented parameter and an output schema present, the description covers the essential behavior: scope, status handling, and presentation constraints. Nothing critical is missing for an agent to invoke it 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?

Schema description coverage is 100%: the only parameter, user_id, is fully documented with its meaning and default. The description adds no extra parameter-level semantics, so 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 a specific verb ('List') and resource ('faxes in the outbox') with a clear scope ('waiting to be sent'). This distinguishes it from siblings like list-faxes (all faxes) and get-outbox-fax (single fax). No ambiguity about what the tool does.

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 use for outbox faxes waiting to be sent, but it does not explicitly name alternatives or provide when-to-use/when-not-to-use guidance. The sibling list-faxes exists, but no routing guidance is given.

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