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

Annotations already declare readOnlyHint=true, idempotentHint=true, and destructiveHint=false, so the safety profile is covered. The description adds useful context about what is validated (MER envelope, canonical evidence links, Ed25519 proof) and the risk level (R1; PUBLIC), which goes beyond the annotations. It does not describe output format or failure behavior, but with no output schema and strong annotations, this is a moderate gap.

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 two sentences with no wasted words. It front-loads the core action ('Validate the public MER envelope...') and adds the key context ('without trusting marketplace claims') and risk classification ('Risk R1; PUBLIC') efficiently.

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, idempotent tool with no output schema, the description covers the essential behavioral context: what is validated, the trust model, and the risk level. It does not describe the return value or error cases, but the absence of an output schema and the simplicity of the operation make this a minor gap.

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 has 0 parameters, so the schema provides no parameter documentation. The description compensates by explaining what the tool validates, which is the only relevant semantic context. With no parameters to document, a baseline of 4 is appropriate.

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 ('Validate') and resource ('public MER envelope, canonical evidence links, and sandbox Ed25519 proof'), which clearly identifies what the tool does. It does not explicitly distinguish itself from siblings, but the sibling names are unrelated enough that confusion is unlikely.

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 usage context by mentioning 'without trusting marketplace claims' and 'No commercial obligation', which suggests when to use this tool (for verification independent of marketplace trust). However, it does not explicitly state when not to use it or name alternative tools for related verification tasks.

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