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

Annotations already declare readOnlyHint=true, idempotentHint=true, and destructiveHint=false. The description adds valuable context by disclosing that the tool is 'Subscription-gated' and that it does not return raw SQL, which are behavioral traits not covered by annotations. No contradictions found.

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 a single, front-loaded sentence of 13 words: 'Subscription-gated explanation of fields, evidence requirements, and SQL fingerprint without raw SQL.' Every phrase adds meaningful information, with no wasted words or repetition.

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 presence of an output schema and comprehensive annotations, the description sufficiently explains the tool's purpose. It covers key aspects (fields, evidence, SQL fingerprint) and the subscription constraint, making it complete enough for an agent to decide on invocation. A slightly richer description of what 'signal' means would push this to 5, but it is not necessary.

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 has 100% description coverage for all six optional parameters, so the description does not need to explain them. Baseline 3 applies since the schema carries the full burden and the description adds no extra parameter-level 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 clearly states the tool provides 'explanation of fields, evidence requirements, and SQL fingerprint without raw SQL', using a specific verb (explain) and resource (signal). The phrase 'without raw SQL' distinguishes it from SQL-returning tools like atlas7_compile_query, making the purpose uniquely identifiable.

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 implies when to use (when an explanation is needed) and gives a clear exclusion ('without raw SQL'), but it does not explicitly name alternative tools or state 'when not to use'. Usage context is implicit rather than explicit, so it falls short of a 4 or 5.

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