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

Annotations already declare readOnlyHint=true and destructiveHint=false, so the safety profile is covered. The description adds genuine behavioral detail by listing possible return states and noting that failed faxes include a reason the agent can act on, which goes beyond what the annotations provide.

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?

One tightly written sentence front-loads the core behavior, then packs the state list and the actionable failed-fax note without wasted words. Every clause contributes useful information.

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 one-parameter, read-only status lookup, the description gives the agent the essential return vocabulary and the failure-reason behavior. It is slightly thin on the exact response envelope, but no output schema exists and the expected values are clearly named.

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 0%, and the description does not explain how to obtain fax_id or that it is the identifier returned by send_fax. The phrase 'of a fax' merely echoes what the property name already implies, so the description adds little parameter-level meaning.

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 title 'Check fax status' and the opening phrase 'Current delivery state of a fax' clearly identify the resource and the operation. The enumeration of concrete states (awaiting_payment, paid, submitted, sending, delivered, or failed) makes it easy to distinguish this status tool from get_fax_receipt, quote_fax, and send_fax.

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 implies this tool is for monitoring delivery and investigating failures, especially through the actionable failed-reason detail, but it never explicitly says when to prefer it over get_fax_receipt or other siblings. The usage context is inferable rather than stated.

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