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

Annotations already declare readOnly, idempotent, non-destructive and closed-world, so the safety profile needs no restating and the description correctly avoids it. It adds real context beyond annotations: the return shape (ids, titles, urls to cite) and the note that type='tool' lists calculators you can call without searching. It doesn't mention ranking, empty-result behavior or pagination past limit, so not a 5.

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?

Three front-loaded sentences: scope, return contract, then exclusion. The parenthetical topic list is long but functional, serving as searchable subject matter. Slightly dense but nearly every clause 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 a rich annotation set and an output schema, the description doesn't need to explain return values or safety, and it correctly focuses on routing. Scope, exclusions and the id-to-fetch handoff cover what an agent needs; only ranking/result-volume behavior is left implicit, which is minor.

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 67% with strong enum and query descriptions, so the schema carries most parameter meaning. The description's only parameter-adjacent contribution is the note that calculators can be called without searching, which the enum description already states; limit and query semantics get nothing extra. 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 verb (search) plus the exact resource set (guides, templates) and enumerates the guide topics so an agent can match intent. It also distinguishes itself from the fetch sibling by saying it returns ids to pass to fetch, which no schema field conveys.

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 names what the tool is NOT for (mass, volume, dilution, master mix, LNP formulation, plate map) and routes to the correct alternative ('call that calculator directly'). The sibling list (serial_dilution, pcr_master_mix, plate_map, lnp_formulation, solution_prep) maps cleanly onto those excluded cases, leaving little inference.

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