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

Annotations cover the safety profile, and the description adds substantial behavioral detail beyond them: whitespace stripping, exact case-sensitive matching, the fact that Duplicates and Invalid are reported separately from Created, and the module/403 prerequisite. Idempotency is declared non-idempotent, and the return-counting instruction is a genuinely useful operational warning.

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?

Front-loads the core action, then routes to the alternative, then enumerates rules, then the response behavior and prerequisite. Dense but every sentence carries distinct, non-redundant 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?

Given the 7-parameter mutation tool with no output schema, the description supplies the return-shape behavior (Created/Duplicates/Invalid), the validation constraints, and the auth prerequisite. Nothing critical to correct invocation 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 coverage is 100%, so the schema already documents all seven parameters, giving a baseline of 3. The description adds meaning beyond the schema by explaining code validation behavior (whitespace stripped, exact case-sensitive matching) and that value/description/etc. are shared across the whole batch.

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 a specific verb and resource with explicit scope: 'Add 1 to 1,000 codes you ALREADY have ... to a sweepstakes.' It directly contrasts with the sibling generate_codes, so an agent can select it without opening either schema.

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?

Names the alternative (generate_codes) and the exact condition that selects it ('To have Sweeppea invent the codes for you'). It also tells the agent when-not via the 'already have' framing and handles the 403 case with explicit 'do NOT retry' guidance.

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