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

Annotations already declare readOnlyHint, openWorldHint, idempotentHint, and no destructive behavior. The description adds context: it returns genuine statewide totals, plug-in counts, and covers entire fleet. No contradictions.

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 somewhat long but front-loaded with key purpose and usage. Every sentence adds value, though minor redundancy could be trimmed. Overall good structure.

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 4 parameters, no output schema, and moderate complexity, the description is very complete. It explains return content (counts by county, total, plugin count) and example questions, leaving no major 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 coverage is 100% with descriptions for all 4 parameters. The description adds extra context like default values for year and quarter, and examples (e.g., Allegheny county). It complements the schema well.

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 clearly states the tool counts all vehicles registered in Pennsylvania by county for a given quarter, from PennDOT Driver & Vehicle Services. It specifies it covers all fuel types, returns a statewide total, and distinguishes from the sibling tool pa_dmv_ev_adoption for electric/hybrid breakdown.

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 when to use: for questions about total registered vehicles, county counts, and quarterly trends. It also directs users to pa_dmv_ev_adoption for electric/hybrid breakdown, providing clear alternative guidance.

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