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

Annotations already declare readOnlyHint=true and idempotentHint=true, so the safety profile is known. The description adds valuable behavior: the wait_seconds timing, the 4xx expectation, and the style guidance for summarizing results. Consistent with annotations, no contradiction.

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 well-structured: purpose first, then operational guidance, then a note about 4xx, then user-facing behavior. The side-effects line is redundant with annotations but short. No filler.

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?

With an output schema present, return values are covered. The description addresses purpose, timing, error expectations, and user presentation. For a simple read tool with annotations already covering safety, nothing an agent needs is missing.

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 baseline is 3. The description adds meaning beyond the schema by explaining the wait_seconds usage in context (first check vs later polls), which helps the agent decide values. It doesn't explain all params, but the schema does.

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?

States 'Get details of a fax scheduled for sending (outbox)' — a specific verb and resource with clear scoping to outbox, distinguishing it from get-fax (for sent/received) and list-outbox-faxes (for listing). No ambiguity.

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?

Provides concrete usage context: 'After send-fax-uploaded, pass wait_seconds=30 on the first check' and explains the expected 4xx behavior. It doesn't explicitly contrast with sibling get-fax or list-outbox-faxes, but the scenario is clear enough.

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