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

Annotations already establish readOnlyHint, idempotentHint, and non-destructive behavior, so the safety profile is covered. The description adds meaningful behavioral detail beyond the annotations: it searches all 50 titles of the current CFR and enumerates the exact return fields (citation, hierarchy heading, snippet, effective date, URL, total count). This gives the agent a clear model of what the tool will do and return.

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 two sentences with no wasted words. The first sentence states the action and scope, and the second sentence enumerates return fields and points to the relevant alternative. The most decision-relevant information 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 simple two-parameter search tool with strong annotations and full schema coverage, the description is complete. It tells the agent what is searched, what is returned, and when to use a different tool. Although there is no output schema, the description enumerates the return fields, so the agent knows what to expect.

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 input schema already documents both parameters (query and limit) with descriptions and defaults. The tool description adds no additional parameter-level meaning beyond restating that the query is a phrase or keywords. Baseline 3 is appropriate because the schema carries the parameter documentation fully.

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 opens with a specific verb and resource: 'Full-text search the current Code of Federal Regulations (eCFR, all 50 titles)'. It clearly defines what the tool does, including the kind of output it returns (matching sections with citations, hierarchy heading, snippet, effective date, URL, total match count), and it explicitly distinguishes itself from reg_cfr_section by directing full-section reads there.

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 gives an explicit routing instruction: 'Use reg_cfr_section to read a full section's text.' This tells the agent when to prefer the sibling tool instead of reg_cfr_search. It clearly positions reg_cfr_search as the tool for finding relevant sections, not for retrieving complete regulatory text.

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