User-Agent Parser

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

Beyond annotations (readOnlyHint=true), describes billing, cache behavior, error conditions (empty/null returns 400), and limitations (only parses explicit uaString, not headers). Adds substantial behavioral context.

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?

Packed with useful info but slightly verbose with full list of return fields. Could be more concise, but still well-structured and front-loaded with key points.

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?

Comprehensive: covers billing, constraints, sibling differentiation, return field types, error handling, and cache behavior. Despite no output schema, description fully explains 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 coverage is 100% but description adds crucial context: uaString must be exact non-empty, force_refresh bypasses cache only on user request, and cost implication of force_refresh. Adds meaning beyond schema.

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?

Clearly states it's a read-only user-agent parser via POST /v3/user-agent. Specifies input (uaString) and output fields, distinguishing it from sibling bulk_parse_user_agent.

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?

Explicitly mentions cost (1 credit per string), notes it cannot read caller headers, and directs users to bulk_parse_user_agent for multiple strings. Provides clear when-to-use and when-not-to.

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