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

Annotations already cover the read-only, idempotent, non-destructive safety profile, but the description adds real context beyond them: the authentication requirement (free account needed, anonymous calls refused) and the meaning of results (each scanned copy flagged full-view or limited by its rights code). It does not discuss throttling or failure modes, but the auth and result-semantics disclosures are substantive.

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 tight sentences: capability first, then return shape, then the access prerequisite. Every sentence carries information an agent needs, and the most important framing (what the tool does) is front-loaded.

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 responsibly explains the return shape (bibliographic record plus all scanned copies with rights flags). Both parameters are fully documented in the schema, and the auth prerequisite is covered, leaving no gap an agent would need to fill before calling.

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 the enum already enumerates the six identifier types, so the description's restatement of the same list adds little. Baseline 3 is appropriate; no syntax, normalization, or conflict-handling guidance is added for the id value.

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 (look up) and resource (HathiTrust digitized-book holdings) and enumerates the identifier types accepted (OCLC, LCCN, ISSN, ISBN, htid, record number). An agent can immediately tell this is an identifier-based bibliographic lookup, distinct from siblings like get_record or check_full_view.

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?

The description makes clear when the tool applies (you have a standard identifier) and adds a hard prerequisite (free Pipeworx account; anonymous and X-API-Key-only calls refused). However, it never names alternatives such as get_record or check_full_view, nor states when NOT to use this tool, so routing guidance is implied rather than explicit.

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