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

Annotations already declare read-only, idempotent, non-destructive behavior, but the description adds meaningful context beyond them: return fields, coverage='none' fallback behavior, reliability scoring, and concrete rate limits. No behavior contradicts the annotations.

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?

Dense but efficient: the first sentence establishes priority and trigger conditions, the middle explains mapping and returns, and the last routes keyword/slug searches to the sibling tool. Every sentence contributes to selection or invocation.

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?

Complete for a discovery tool: it covers trigger conditions, output shape at a high level, fallback behavior, rate limits, and sibling routing. An output schema exists, so the description need not fully restate return values, and what it does include is sufficient.

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 parameters are already fully documented in the schema. The description adds a plain-language example for the need parameter, but does not materially deepen the semantics of limit, category, or min_reliability beyond what the schema provides.

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 and resource: maps a plain-language goal to callable APIs, MCP servers, or CLIs. It also names the sibling search_registry and distinguishes its own keyword/slug-free discovery role, so an agent can tell the two apart without opening schemas.

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?

Gives explicit when-to-use guidance: call first when a task needs an external service or when a service is failing. It also names the alternative for known keywords/slugs: use search_registry, leaving little to inference.

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