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

With no annotations provided, the description carries the full burden of behavioral disclosure. It transparently explains what happens in both modes: returns a matched certificate with specific fields when an address is given, and returns all certificates with aggregated statistics when no address is given. It does not mention edge cases like invalid postcodes or no match, but for a read-only data retrieval tool this is reasonably transparent.

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 concise and well-structured: a one-sentence summary followed by two clear bullet-like paragraphs for each mode. Every sentence serves a purpose, with no redundancy or filler. The front-loaded main clause immediately states what the tool does, making it easy for an agent to parse quickly.

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 moderate complexity (two modes, two parameters) and the presence of an output schema, the description is sufficiently complete. It explains the return values for both modes, covers the parameter interactions, and provides usage guidance. There are no significant gaps that would prevent an agent from correctly invoking the tool.

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?

The input schema already includes full descriptions for both postcode and address, so baseline is 3. However, the description adds meaningful context beyond the schema by explaining how the address parameter conditionally changes the tool's behavior (exact match vs area aggregation) and how the postcode is used in both modes. This elevates the parameter semantics beyond mere field definitions.

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 provides EPC certificate data for a UK property or postcode area, and distinguishes two distinct modes (with/without address) with specific return details. The verb 'returns' and resource 'EPC certificate data' make the purpose specific and distinct from sibling tools like property_report or planning_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 clear context on when to use each mode: with address for single-property exact match, without address for area-level aggregation and analysis. It explicitly states 'Use this for area analysis rather than a single-property lookup,' which provides directional guidance, though it does not name alternative sibling tools for comparison.

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