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 covered. The description adds useful behavioral context by disclosing what is returned (tariff counts and how many are still current) and that the directory search mode is triggered by filter rather than location.

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?

Three sentences, front-loaded with the primary purpose before the use-case framing and the filter alternative. No filler, though the trailing filter sentence overlaps with schema text.

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?

With no output schema, the description usefully enumerates the return content (serving utilities, tariff counts, sectors, current-tariff count) and mentions the API-key option. It is complete enough to call correctly, though it doesn't warn about ambiguous geocoding or multi-utility results.

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 all five parameters are already documented in the schema. The description restates the filter-vs-location duality ('Pass filter instead of a location'), which largely duplicates the schema's own 'Instead of a location' wording, so it adds little beyond the baseline.

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?

States a specific verb (find) and resource (electric utilities serving a US location), plus the returned fields (tariff counts, sectors, current tariffs). An agent can distinguish it from rate-lookup siblings like urdb_search_rates without opening any schema.

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?

Frames the tool as the 'who is the utility at this address' step that precedes looking for rates, giving clear sequencing context. It also documents the alternate mode (filter instead of location), but never names urdb_search_rates or urdb_rate_detail as the follow-on alternatives explicitly.

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