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

Annotations already provide readOnly, idempotent, and non-destructive hints, and the description adds substantial behavior beyond those: the exact HTTP GET mechanism, the three-state output contract (VALID, INVALID, UNCHECKABLE), the failure mode for an unreachable endpoint, and limitations around Ed25519. This is rich, non-redundant context.

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?

Three sentences, each carrying unique information: the action and endpoint, the allowed return states, and the explicit non-claims. The most important information is front-loaded, and there is no filler.

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?

With a single well-documented parameter, complete annotations, and an output schema, the description still covers the essential behavioral details an agent needs: the endpoint, the three possible outcomes, and the failure mode. Nothing required for correct invocation 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?

The input schema already fully documents the only parameter as a '64-char hex digest', so schema-description coverage is 100%. The description does not add parameter-level meaning beyond the schema, so the baseline of 3 applies.

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 a sha256 against the live public-root merkle via GET /api/proof?sha='. It also distinguishes itself from sibling tools by explicitly excluding Ed25519 claims and grading, making its scope unmistakable.

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 exclusions: it does not claim Ed25519 and is never a grade, which tells an agent when not to use it. However, it does not name an alternative sibling tool or state a positive 'use this when...' condition, so it stops short of fully explicit routing.

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