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

Annotations already declare readOnlyHint=true, ensuring the agent knows this is a safe read operation. The description adds the dual input forms (id or display name) and lists return categories, but these are already covered by the schema and output schema. It discloses no side effects or unexpected behaviors beyond what structured fields provide.

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?

Two sentences, front-loaded with the core purpose and no filler. The second sentence efficiently explains input format and provides referral guidance, making every word earned.

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?

Given the 100% schema coverage, presence of readOnly annotation, and an output schema, the description is fully adequate. It covers purpose, input format, and usage guidance without unnecessary repetition, leaving 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?

The input schema already fully documents both parameters (feature_id and include_mdn) with descriptions, examples, and defaults. The description does not add any parameter meaning beyond the schema, so the baseline score of 3 is appropriate.

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 specifies the verb 'Get' and resource 'one CSS feature' while enumerating exact data returned (Baseline status, browser versions, spec links, etc.). It clearly distinguishes this tool from the sibling search_css_features, as it targets a single known feature rather than searching.

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 instructs 'Use search_css_features first if you do not know the id,' providing a clear alternative for a common scenario. It also implies this tool is for comprehensive detail retrieval on a single feature, contrasting with the search tool.

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