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

Beyond the annotations (readOnly, idempotent), the description adds concrete behavioral context: never raises a protocol error, returns an error object with corrective guidance, and explicitly confirms that retrying is safe. This significantly exceeds what annotations already 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?

The description is longer than average but every sentence adds value (purpose, usage, example, error handling, safety). The 'FREE' note is unnecessary noise but doesn't obscure the core content. Format is front-loaded with purpose and example.

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?

Given the tool's moderate complexity (5 params, output schema), the description covers all key aspects: calculation logic, example output, error behavior, idempotency, and usage context. No significant gaps remain.

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%, so the baseline is 3. The description adds a concrete example with typical inputs and outputs, clarifying the buffer concept and error format, which helps agents understand parameter relationships beyond the schema.

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 clearly states the tool's function: turning supplier and transit times into a promise date, with a specific example. It distinguishes itself from siblings by explicitly saying it is not for shipping costs and pointing to a separate shipping server.

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 explicit when-to-use guidance ('when writing a shipping policy or answering when will it arrive') and an explicit exclusion ('Not for what the shipping costs'), which clearly differentiates it from related tools.

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