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

Annotations already declare read-only, idempotent, non-destructive and closed-world, and the description partly restates that. The genuinely additive content is the error contract: invalid input never raises a protocol error but returns {"error": ...} with a fix hint, plus the explicit safe-to-retry guarantee. Return-shape detail is unnecessary given the output schema exists.

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-loaded with purpose, then example, then usage boundary, then error behavior — a sensible order. The lone 'FREE.' fragment is marketing noise that earns no place, but the rest is dense and useful.

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 annotations covering safety, an output schema covering return values, and full schema coverage on parameters, the description closes the remaining gaps: when to use versus not, and how failures are surfaced. An agent has everything needed to call it correctly and recover from bad input.

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 the schema already documents all eight parameters, including the 'Last, First' author format and style casing. The worked input/output example reinforces composition but largely restates what the schema says, so baseline 3 applies.

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 (format a citation) and names the three supported styles (APA 7, MLA 9, Chicago author-date). It also distinguishes the tool from siblings by declaring what it does not do: find or verify a source.

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?

Explicit routing: "Use when the source details are already known and only the formatting is missing. Not for finding or verifying a source." Both the positive condition and the exclusion are stated, leaving nothing to inference.

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