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

Annotations already declare readOnly, idempotent, openWorld, and non-destructive, so the safety profile is fully covered in structured data. The description adds nothing behavioral beyond that — no rate limits, no indication of whether results reflect current eCFR text only, and no sense of result size. It also does not contradict the annotations.

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 operation, then the narrowing facets. The agency parenthetical is dense but every token in it carries selection value for an agent; nothing is redundant with the title or annotations.

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 four-parameter, fully documented search tool with no output schema, the definition covers what is needed to call it. It leaves minor gaps: no statement of what a result contains (citation, text snippet, URL), no cap on 'limit', and no indication of whether historical versions are searchable — relevant given the existence of cfr_changes.

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 the baseline is 3, but the description earns above-baseline credit by mapping CFR title numbers to agencies (29 OSHA, 49 DOT/FMCSA/PHMSA, 46/33 Coast Guard, 40 EPA) — domain knowledge the schema's bare 'CFR title number' does not supply. The 'part' parameter gets no comparable elaboration.

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 first sentence states a specific verb and resource — full-text search over the Code of Federal Regulations — and the second adds the narrowing dimensions (title, part). It does not explicitly distinguish itself from siblings such as cfr_lookup or cfr_changes, so an agent must infer that this is the discovery tool versus a section-retrieval or change-tracking tool.

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?

Usage is implied by 'full-text search' plus the title/part narrowing hint, which tells the agent this is for keyword discovery within known titles. There is no explicit when-to-use vs when-not-to-use guidance, and no mention of the sibling tools that would be better for retrieving a known section or checking recent amendments.

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