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

The description discloses why the tool is unsupported: reproducing the old response would require one upstream request per certificate, making it silently expensive. This goes beyond the readOnlyHint annotation (which confirms it's read-only) and explains the behavioral trade-off. No contradiction.

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. The deprecation notice is front-loaded, the old purpose is stated in one sentence, and the rationale is given in a short final sentence. Every sentence earns its place with no fluff.

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?

For a deprecated tool, this is complete: it explains what it did, why it's unsupported, and what to use instead. The output schema exists but is not needed since the tool should not be invoked. An agent has all the information required to route correctly.

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 schema has 0% description coverage and the description does not elaborate on the postcode parameter beyond mentioning 'every certificate at a postcode'. However, the sole parameter is self-explanatory and the tool is deprecated. The description minimally compensates, but not fully—hence a baseline 3.

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 is deprecated and explains exactly what it used to do (returned score, floor_area, property_type, habitable_rooms, inspection_date for every certificate at a postcode). It also explicitly names the recommended alternatives, distinguishing it from them. An agent immediately knows this tool should not be called and what to use instead.

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?

It explicitly says 'DEPRECATED — use property_epc_summaries then epc_certificate', giving a direct replacement and the correct ordering. It also explains why (unsupported rather than silently degraded or expensive), which helps the agent understand the context and avoid wasting calls.

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