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

Annotations already declare readOnlyHint=true, idempotentHint=true, and destructiveHint=false, so the safety profile is covered. The description adds useful behavioral context: it returns exactly one record, accepts either id or name keyword, and explicitly disclaims legal opinion and applicability assessment. It doesn't describe pagination or error behavior, but for a single-record read tool with strong annotations, this is solid.

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 well-structured with clear sections (Purpose, Guidelines, Limits, Ex) and every sentence earns its place. It front-loads the purpose, then gives actionable usage guidance, then limits, then examples. No fluff or repetition of schema content.

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 single-record read tool with an output schema present, the description covers everything an agent needs: what the tool returns, how to identify the record, when to use the sibling search tool, and what the tool does not do. The output schema handles return-value details, and annotations handle safety. No critical gaps.

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 the schema already documents all four parameters. The description adds value by explaining the id/name mutual exclusivity ('与 id 二选一' is in schema, but description reinforces it), giving concrete example values (rcb-pol-001, CBAM, 2023/956), and clarifying that response_format='json' is for agent pipelines. This goes beyond the schema's terse descriptions.

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 states a specific verb ('fetch') and resource ('one regulation record in full') and enumerates the exact fields returned (issuing body, policy type, scope, impact, compliance deadline, source link, AI-readable summary). It clearly distinguishes from siblings like query_policies (search) and get_announcements_timeline (timeline) by focusing on a single regulation record.

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 description explicitly says to run query_policies first when the id is unknown, and provides concrete examples for both id and name/identifier keyword usage. It also states limits (one record per call, no legal opinion, no applicability assessment), which helps the agent decide when not to use this tool.

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