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

Annotations already declare readOnlyHint and idempotentHint, but the description adds substantive behavior beyond them: it does not edit the file (the host agent applies resolutions), and on the hosted stateless endpoint it returns a delegation envelope unless artifactFiles is supplied. That endpoint-specific failure mode is exactly the kind of context annotations cannot express.

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?

Front-loaded with phase, verb, and return payload, and every sentence carries information. The dedicated 'Parameter relationships' sentence partially restates the schema's feature description, which is the only mild redundancy.

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 an output schema present, return values need no explanation, and the description still covers the delegation-envelope fallback and the read-only contract. Nothing an agent needs to call this correctly — required param, precondition, and hosted-endpoint caveat — 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?

Schema coverage is 100%, so the baseline is 3, but the description adds a real constraint beyond the schema: feature 'must be the exact spec directory name created by vdd_specify', and it explains the consequence of omitting artifactFiles on the hosted endpoint. It stops short of clarifying how projectRoot interacts with artifactFiles resolution.

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 ('Clarify an existing spec — scans vdd/specs/<feature>/spec.md and returns the items to resolve') and enumerates exactly what it returns (markers, [e.g.] placeholders, AC-E counterparts). It explicitly distinguishes itself from the sibling vdd_specify, so an agent can route without opening either 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 trigger ('Run after vdd_specify when a spec has unresolved markers') and names the alternative for the opposite case ('to author a brand-new spec use vdd_specify instead'). When-to-use, when-not-to-use, and the alternative are all present.

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