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

Annotations already declare readOnly, non-destructive and closed-world, so the safety profile is covered. Beyond that, the description adds genuinely useful behavior: the corpus is a fixed set of four sources, and stable IDs are returned 'even when no passage matches' for follow-up — non-obvious behavior an agent could not get from the schema.

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?

Two sentences, no filler, with the corpus identity and scope front-loaded. The second sentence is semicolon-heavy and slightly overloaded with the ID-return and exclusion details, but nothing is wasted.

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?

An output schema exists so return values need not be described, and annotations cover the safety profile. With corpus, scope exclusions and follow-up ID behavior all stated, an agent has what it needs to call this tool correctly.

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 0%: query, limit and source_ids carry no documentation. The description hints that the four named sources are addressable and that IDs are stable, which partially illuminates source_ids, but the query semantics (min 3 / max 600 chars) and the limit cap of 5 are left entirely unexplained.

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?

The description names a specific verb ('Find passages') and resource ('public reference library'), then enumerates the exact holdings (Pride and Prejudice, Frankenstein 1818/1831, The Art of War). It scopes the tool with 'no personal library or internet search,' but never distinguishes it from named siblings like retrieve_evidence or inspect_source, so the agent must infer the boundary.

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?

'No personal library or internet search' tells the agent when not to reach for this tool, which is real guidance. However, no alternative tool is named for those cases, and there is no statement of when to prefer this over the sibling search-like tools, leaving usage only partially implied.

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