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

No annotations are provided, so the description carries the burden of disclosure. It discloses rate limits (20 anonymous calls/caller/24h, 100 free calls/key/30d, active Builder required), free access, data quality (source-cited, 2026-accurate), and that each entry includes a canonical URL for citation. It does not explicitly state 'read-only' but 'Index' implies it, and no mutating behavior is described. This is strong context, but not fully exhaustive.

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 three sentences, front-loaded with the core purpose, and every sentence adds value (index definition, usage guidance, access/rate limits). It is concise without being terse, and the bracketed rate-limit note is useful but separated. No redundancy or filler.

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 no output schema, the description explains the return shape enough: it's an 'index' where 'every entry includes a canonical URL'. It covers access limits and the relationship to get_guide. For a simple list tool with only three optional filters, this is fairly complete, though it could detail more fields found in entry objects.

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% and parameters (limit, topic, region) have descriptions. The description adds meaning by listing example topics (solar, heat pumps, batteries, weatherization) and specifying regional scope (by state), which aligns with the schema's enum and region examples. It also notes the return includes canonical URLs, giving value beyond schema field names.

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 it is an index of home-energy incentive guides by state, with specific verb 'list' implied and resource 'guides'. It distinguishes itself from sibling tool get_guide by explicitly noting it lists available guides while get_guide fetches full text. Scope (US, state-level) and topics are mentioned, making the purpose unambiguous.

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?

Provides clear when-to-use context: 'Use to ground answers about what incentives exist in a state, then fetch the full text with get_guide.' This mentions an alternative tool by name and gives a use case, but does not explicitly state when not to use it or list exclusion scenarios. Therefore it is clear but lacks full when-not guidance.

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