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

Annotations already cover safety profile (readOnlyHint, idempotentHint, destructiveHint). The description adds valuable behavioral details: case-insensitive substring matching, limit semantics, and the specific response fields. This goes beyond what annotations convey.

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 with no wasted words. The core action is front-loaded, followed by usage context and matching behavior. Every sentence 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?

The description covers the essential trigger scenario, parameter behavior, and return fields, which is complete for a simple read-only search tool despite lacking an output schema. The only gap is not addressing how this tool relates to sibling tools that might also perform searches, like find_similar.

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 67%, meaning the limit parameter lacks schema-level description. The description compensates by explaining that 'Returns up to limit matches' and by defining query as a case-insensitive free-text name search. Country is already described in the schema, but the added clarity for query and limit is meaningful.

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 clearly states the tool's purpose: 'Search the charity registry by free-text name' and lists the return fields. This is a specific verb and resource. However, it does not explicitly distinguish itself from sibling tools like find_similar, so it falls short of a 5.

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?

Provides an explicit usage scenario: 'Use this BEFORE resources/read when the user names a charity but you don't know its slug.' This is clear context for when to use it. It lacks explicit guidance on when not to use it relative to the listed siblings (compare_charities, find_similar, verify_charity).

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