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

Annotations already declare readOnly/idempotent/non-destructive, so the safety profile is covered. The description adds non-obvious behavior beyond that: filters are exact tags, multi-framework queries combine with AND, and results are sorted by name rather than ranked relevance. Not revealing, but genuinely additive.

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?

Four short sentences, front-loaded with what is searched, then the tag semantics, the routing hint, and the sort guarantee. No filler and nothing buried.

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 an openWorldHint=false read tool with a fully documented schema and no output schema, the description covers purpose, filter semantics, result ordering, and a routing hint to list_categories. It omits any mention of result shape or how q maps to matched dimensions, but the essentials for correct invocation are present.

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 baseline is 3, and the description earns above baseline by clarifying that all filters are exact tag matches and that frameworks are AND-combined — semantics that are only partially echoed in the schema. It does not add per-parameter detail for q/limit/regions/service_types beyond what the schema already says.

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 + resource and domain: 'Search the ISMS Directory catalog of ISO 27001, SOC 2, GDPR, DORA, NIS 2 ... compliance service providers (consultants, auditors, platforms, training).' It also names the sibling list_categories and its role, so an agent can separate this from the lookup tools 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?

Explicitly routes tag discovery to list_categories ('Use list_categories first if you are unsure of a tag') and warns filters are exact tags, which is real usage guidance. It does not state when NOT to use this tool versus get_service_details or check_if_listed, so it stops short of full when/when-not coverage.

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