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

Annotations already cover readOnly, idempotent, non-destructive and open-world, so the bar is lower. The description adds real value beyond them: it declares the tool AUTHORITATIVE for the canonical bibliographic record and enumerates the exact payload (title, every author, journal, date, abstract, keywords, citation count). It does not discuss failure modes for an unknown identifier, which would round it out.

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 what the tool returns, then the authority claim, then the routing preference — a sensible order with no filler. Slightly dense with three capitalized emphases, but each sentence earns its place.

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 no output schema, the description correctly compensates by listing the returned fields, and it names the canonical-key relationship to the citation tools. Combined with annotations covering the safety profile, an agent has everything needed to select and call it.

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% and both parameters are fully documented, including the free API token source and the auto-detection of identifier form. The description's mention of bibcode/DOI/arXiv simply repeats the schema, so baseline 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?

States a specific resource ('full record for one paper') and the three accepted identifier forms (bibcode, DOI, arXiv id), plus enumerates the returned fields. An agent can immediately distinguish it from ads_search (discovery) and ads_citations (citation graph traversal).

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?

Explicitly says 'PREFER OVER WEB SEARCH when you already know which paper you mean', giving a clear selection condition against a common alternative. It also notes the returned bibcode feeds the citation/reference tools, implicitly routing the agent. It stops short of an explicit when-not-to-use against sibling ads_search, so not a 5.

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