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

With readOnlyHint already present, the description adds important behavioral context beyond annotations: results are one bounded page, complete may be false when more records exist, page traversal is not snapshot-stable, an empty results list means no certificates, and an unreachable EPC service raises an error rather than returning empty. These are valuable edge-case disclosures that prevent misinterpretation.

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 detailed but every sentence earns its place: purpose, field limitations, workflow, ambiguity handling, pagination caveat, and empty/error semantics. The most important facts are front-loaded, and the structured workflow makes the text easy to follow without being verbose.

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 the tool's role in a multi-step EPC lookup workflow and the existence of an output schema, the description is complete. It covers what the tool returns, what it deliberately omits, how to continue the workflow, how to handle ambiguity, and how to interpret empty versus error results. No critical operational context is missing.

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 description coverage is 0%, so the description carries the burden for parameter meaning. It clearly ties the postcode parameter to the lookup scope and explains page-related behavior via the 'bounded page' and 'complete is false' semantics. It does not explicitly state the page parameter's role or postcode format requirements, but the schema's default and the surrounding text make the main usage sufficiently clear.

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 opens with a specific verb and resource: 'List EPC certificate summaries at a postcode — for candidate selection.' It clearly distinguishes itself from certificate retrieval by saying 'Energy score, floor area and property type are NOT available here — fetch a specific certificate for those.' This makes it easy for an agent to tell it apart from siblings like prop_property_epc_certificate and prop_property_epc_search.

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 gives an explicit numbered workflow for when a Rightmove listing has no house number, assigning this tool to step 1 and prop_epc_certificate to step 3. It also provides exclusion guidance: do not guess when several candidates remain, and do not treat an error as evidence of no certificate. This is clear when-to-use and when-not-to-use guidance.

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