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

Annotations already declare read-only, idempotent, non-destructive and open-world, so the safety profile is covered. The description adds real value by disclosing the response shape — aggregate counts first (total matched, by_status, by_country) followed by a page of rows — which is not in any structured field since there is no output schema. It stops short of saying whether counts reflect the full filter set or the page, and row ordering is unspecified.

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 sentences, front-loaded with the resource and filter set, then the return contract, then the one non-obvious query mode. Every sentence carries information, though the operating_mic sentence duplicates schema content and could have been spent on ordering or count semantics instead.

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?

With no output schema, the description correctly takes on the burden of explaining the return payload, and paging is covered by the schema's limit/offset docs. What remains unstated is row sort order and whether the aggregates are computed over the whole filtered set — small but real gaps for an agent paginating results.

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 all six parameters, including the status enum and limit range, are already documented in the schema. The description's operating_mic sentence largely restates the schema's own wording and example ('XNYS'), adding little new semantic content. Baseline 3 applies when the schema does the heavy lifting.

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 — filtering the ISO 10383 MIC registry — and enumerates the filter axes plus the two-part return (counts then rows). It is clear on its own, but never mentions the sibling decode_mic, which is the obvious adjacent lookup tool, so sibling differentiation is left to inference.

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 only genuine usage guidance is the operating_mic sentence explaining the inverse-scope query pattern ('every segment under XNYS'), which is a useful hint. There is no statement of when not to use it, no mention of decode_mic as the alternative for single-code lookups, and no guidance on combining filters.

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