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

Even though annotations already indicate the tool is not read-only, the description adds valuable specifics: successful delivery creates an invoice and emails receipt_email from receipts@sendafax.ai. This discloses side effects and timing that an agent could not infer from annotations alone.

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 front-loaded with the core purpose and remains compact. The final sentence about receiving an email receipt is somewhat redundant with the earlier email side effect, but overall the structure is clear and efficient.

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 single-parameter tool with rich annotations, the description covers purpose, sequencing, auth, and side effects. With no output schema, it does not explicitly describe the shape of the returned status, which keeps it from being fully complete, but this is a minor gap.

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 coverage is 100%, and the schema already describes fax_id as 'SendaFax job id returned by send_fax.' The description references fax_id but adds no format, syntax, or semantic detail beyond the schema, so the baseline score 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 and resource: 'Check delivery status of a SendaFax job by fax_id.' This clearly distinguishes the tool from siblings send_fax and get_coverage, and it adds the sequencing context 'Use after 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 explicitly says to use this tool after send_fax, which gives clear contextual guidance. It does not explicitly exclude sibling tools or provide when-not-to-use conditions, so it falls just short of a 5.

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