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

With no annotations provided, the description carries the full behavioral burden. It discloses the cryptographic verification behavior, the self-attestation path, the self_attested=true flag, and the limitation that self-attestation is only a convenience. It does not describe return/error behavior on invalid signatures, but the disclosed caveats go well beyond the schema.

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 with no filler. The first sentence states the core action and trust requirement; the second provides the critical optional-parameter caveat. Information is front-loaded and every clause earns its place.

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 tool with a nested object, no output schema, and no annotations, the description is largely complete: it defines the operation, the required input, the optional parameter's semantics, and the credibility caveat. The main missing piece is the exact return shape or error behavior on failed verification, which an output schema would normally cover.

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. The description adds meaningful semantics beyond the schema by explaining key provenance for pubkey_hex, the out-of-band confirmation requirement, and the behavioral consequence of omission. It also clarifies that receipt should be a full object returned by vigil_notarize or vigil_get_receipt.

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 opens with a specific verb and resource: 'Verify a receipt's hash and Ed25519 signature against a pubkey you trust.' This clearly identifies the tool's function and distinguishes it from sibling verification tools like vigil_verify_lease and vigil_verify_source by focusing specifically on receipts.

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 explicit guidance for when to supply pubkey_hex versus when it can be omitted, including the source of the trusted key ('from vigil_info, confirmed out-of-band') and a warning that self-attestation is 'not independent proof.' It does not explicitly exclude alternative tools, but it provides strong contextual usage guidance.

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