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

Annotations already provide readOnlyHint, idempotentHint, and destructiveHint. The description adds the important behavioral boundary that it 'never makes a waste-route or permit conclusion' and returns only 'source-health status.' This goes beyond the annotations and helps the agent understand side effects, though it does not elaborate on response format or edge cases.

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 front-loaded with the core purpose and provides essential exclusions in three sentences. The phrase 'FREE EVIDENCE-HEALTH tool' is slightly unconventional but not bloated. Overall it is efficient and well-structured for quick agent parsing.

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 zero-parameter, read-only tool with an output schema and strong annotations, the description covers the necessary aspects: purpose, usage boundaries, and what it returns. It does not need to explain return structure because the output schema exists. Slight gap: it doesn't clarify what 'fresh' or 'decision-usable' means operationally, but that is likely encoded in the output schema.

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?

With 0 parameters and 100% schema coverage, the baseline is 4. The description has no parameters to describe, so it correctly adds no parameter-specific detail. The mention of what it checks (freshness, unchanged, availability) is conceptual context rather than parameter semantics.

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 states a specific verb and resource: 'check whether the reviewed official GOV.UK / Environment Agency evidence is fresh, unchanged, available and decision-usable.' It differentiates from siblings by explicitly saying it never makes a waste-route or permit conclusion, effectively distinguishing it from tools like waste_rule_preflight.

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 explicit when-to-use guidance ('Use only to check...') and clear when-not-to-use instructions ('Do NOT use for operational routing; use waste_rule_preflight or a narrower workflow tool'). It names the alternative, leaving no ambiguity about tool selection.

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