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

Annotations already declare readOnlyHint=true, idempotentHint=true, and destructiveHint=false, so the safety profile is covered. The description adds meaningful behavioral context: it returns specific fields (newspaper, date, city/state, link, image URL), supports filtering by date range and state, and gives a concrete example. It does not disclose pagination or rate limits, but for a read-only search tool this is a minor gap.

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?

The description is three sentences: purpose, return value, and filtering capability, followed by a compact example. Every sentence earns its place, and the most important information (what it searches and what it returns) is front-loaded. The example is illustrative without being verbose.

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 read-only search tool with 100% schema coverage and no output schema, the description is nearly complete. It covers what the tool does, what it returns, and how to filter. The only missing piece is explicit mention of pagination or result limits, but the schema documents the limit parameter (default 10, max 25), so an agent can infer behavior. A 4 is fair; a 5 would require explicit handling of edge cases like empty results or OCR limitations.

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%, so the schema already documents all 5 parameters. The description adds value by showing a concrete usage example with query, date_from, date_to, and state, and by explaining the return fields that the parameters map to. It doesn't add syntax details beyond the schema, but the example and context make the parameters' purpose clearer. Baseline 3 plus the example and return-field mapping justifies a 4.

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 states a specific verb ('search'), a specific resource ('digitized historical U.S. newspapers' from Chronicling America), and the exact scope (full-text, ~1690s–present). It also lists what is returned (newspaper, date, city/state, link, image URL), which clearly distinguishes it from the sibling tools like company_facts or entity_profile. The example further anchors the purpose.

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 clearly implies when to use it: when the agent needs primary-source newspaper coverage of a person, event, place, or topic in U.S. history. It does not explicitly name alternatives or exclusions, but the context signals and sibling list show it is the only newspaper-specific search tool, so the usage context is clear. A 4 is appropriate because it lacks explicit 'use this instead of X' guidance but provides strong contextual cues.

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