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

No annotations, so the description carries full burden and does so well: it discloses auth model (public, no bearer required), the return shape (valid, details, errors, jwks_url, jwks_kids), and the specific validation semantics (every embedded credential's eddsa-jcs-2022 signature must verify). It does not describe rate limits or pagination, but the core behavior is transparent.

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 guidance and return shape are strong, but the JCS canonical form warning is repeated across several sentences with overlapping phrasing, which inflates length beyond what a single crisp warning would need.

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?

Covers when/when-not, the sibling alternative, return fields, and the parameter constraints for a nested-object VC verification tool with no output schema. The return values are described inline as the description must do here. Missing only tangential details like error semantics per failure mode.

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 description coverage is 100%, and the schema documents jwks_url's optionality/derivation and credential verbatim-passing thoroughly. The description reinforces this (don't trim/paraphrase, don't remove proof fields) but adds little the schema does not already say, so the baseline 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?

States a specific verb (verify) and resource (W3C VC/VP credential) cryptographically against the issuer's JWKS. Explicitly distinguishes itself from the sibling verify_credential_by_url by the condition 'when you have the body in hand'.

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?

Provides explicit when-to-use ('when you have the credential body in hand') and when-not-to-use / prefer-alternative guidance (prefer verify_credential_by_url unless the body is local). Names the concrete failure mode (JCS canonical hash breakage) that selects the sibling.

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