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

With readOnlyHint already declared, the description still adds real behavioral context: 'No API key needed' (auth requirement) and a summary of the return payload (slug, version, business rules checked). It does not mention pagination or result-count limits for a no-required-parameter listing search.

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?

Three tight sentences: what is searched, what is returned and where it flows, and the auth note. No filler, and the resource scope is front-loaded.

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 one-optional-parameter search with no output schema, the description covers purpose, searchable fields, return contents and auth. The only gap is result-set behavior (how many results, any limits), which an agent might want before calling it repeatedly.

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% and the schema already gives query examples, but the description adds meaning by enumerating the fields the query matches against (name, namespace, root element, area) and noting that omitting the query lists the first schemas — neither of which the schema states.

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 (search) plus the exact resource (xmlvalid's catalog of official XML schemas) and enumerates the standards covered, so an agent immediately knows the scope. It also distinguishes itself from siblings by naming validate_xml as the consumer of its output.

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 line 'Returns each schema's slug to pass to validate_xml' tells the agent this is the discovery step before validation, giving clear usage context. It does not state explicit when-not conditions or contrast with explain_error/explain_rule, so it stops short of a 5.

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