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

The description adds a side-effect disclosure ('modifies outbox record metadata') beyond the annotations. This helps clarify that the update mutates state without deleting the fax, which complements the destructiveHint=true annotation. It does not contradict any annotation.

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 short sentences with no filler. The core purpose is front-loaded, and the side-effect note earns its place as important behavioral context. Nothing unnecessary is included.

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 low-complexity tool with a complete input schema, annotations, and an output schema present, the description is largely sufficient. It notes the key side effect and constraints, though it leaves alternative-tool routing unaddressed.

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%, so the schema already documents all parameters. The phrase 'comment only' reinforces the payload structure but adds little meaning beyond what the schema's payload.comment property already conveys.

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 uses a specific verb ('Update'), names the resource ('queued outbox fax'), and narrows the operation to '(comment only)'. This clearly differentiates it from related tools like update-fax and bulk-update-outbox-faxes.

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 scope is implied by 'queued outbox fax' and 'comment only', which tells the agent when the tool applies, but it never names alternatives or states when not to use them. No explicit routing to update-fax, bulk-update-outbox-faxes, or delete-outbox-fax is provided.

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