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

Annotations already declare read-only, idempotent, closed-world, so the bar is lower — yet the description adds substantial behavior: results are page-level not article-level, no numeric score, ranked tiers with defined semantics, gap date ranges return an explanatory sentence, the 1964–2001 dLOC run has front-page-only images, and OCR text is untrustworthy and only a lead to the primary record. That is exactly the kind of context annotations cannot carry.

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, trigger and scope before dropping into caveats, and nearly every sentence carries decision-relevant information. It is a single dense paragraph with one genuine redundancy — the 'holding library's copy / page image where the archive holds one' caveat appears twice — which keeps it off a 5.

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?

For a 6-parameter ranked search tool with no output schema, the description compensates by describing the result shape in detail (paper, date, page number, tier, matched terms, three link types) and by pre-empting the two failure modes an agent would otherwise misread: OCR error and date-range gaps. Nothing needed to call or interpret it is missing.

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 100%, so syntax (year/month/day forms, paper aliases, limit bounds) is already handled and the baseline is 3. The description still adds meaning beyond the schema: issue dates are reliable in this corpus, hit counts are pages never articles (constraining how 'limit' should be read), and offset paging operates within the best 150 ranked pages — though the tier vocabulary it explains describes output fields more than input parameters.

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?

Names a specific verb and resource (search the islands' newspapers), scopes it to OCR page-level text over four named titles with date spans, and explicitly separates it from list_papers and from the archive's separate document connector. An agent can distinguish this from siblings 'search', 'list_papers', and 'get_page' without opening a schema.

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?

States the triggering conditions directly ("Use when a question names a paper or a period, or needs paging") and routes elsewhere for the excluded cases: list_papers for gap inventory, the document connector for laws, audits, court records and reports. Exclusions and alternatives are both explicit.

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