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

Annotations already declare readOnlyHint, idempotentHint, openWorldHint=false and destructiveHint=false, so safety is fully covered by structured data. The description contributes the substantive behavioral fact that the payload includes negative coverage (claim types no domain covers), which is genuinely useful beyond annotations. It adds nothing about freshness of the coverage data or how to interpret a partial coverage fraction, so a 3 is fair.

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?

Two sentences, both load-bearing: the first enumerates the return content, the second sets the calling precondition. No filler, and the resource being described is front-loaded in the opening clause.

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, no-output-schema tool the description covers what matters: what comes back and when to call it. The remaining gap is the absence of any sense of the return's shape or how the coverage fraction is expressed, which matters slightly more because no output schema exists to absorb it.

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 tool takes zero parameters, so there is nothing for the description to disambiguate; the baseline for a no-param tool is 4. No parameter claims are made that could conflict with the empty schema.

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?

States a specific verb and resource ("Returns what Certisyn can and cannot verify today") and enumerates the payload contents: coverage fraction and uncovered claim types. That framing makes it self-evidently a capability-introspection tool rather than a verification operation like the verify_* siblings, so an agent can route to it without opening a schema.

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?

Gives an explicit usage trigger: "Read this before promising a user that something is verifiable." That is a concrete precondition for calling it. It does not state when not to call it or point to a specific alternative sibling for the actual verification step, which keeps it below a 5.

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