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

With no annotations, the description carries the full burden, and it does well: it discloses the signature algorithm, the log's append-only nature, the signing key relationship to null_prov_issuer, public visibility, and the equivocation-detection property. It does not explicitly state there are no side effects, but the zero-parameter read-style nature makes that relatively clear.

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?

Three dense sentences each earn their place: one defines the signed object, one ties it to the issuer key, and one explains usage and audit significance. No fluff or repetition.

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, no-output-schema tool, the description is complete: it states the data structure, the signature scheme, the issuer relationship, the expected client behavior, and the public-audit context. An agent has everything needed to call and interpret this tool correctly.

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 zero parameters and the schema is already complete, so the description needs to add little here. It still provides useful context about what the returned head contains, which compensates for the absence of an output 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?

The description precisely identifies the resource: an ML-DSA-signed head {seq, root, sig} of the append-only mailbox binding log. It distinguishes the tool from null_witness_range by explaining that a later head must extend the previous one and that the range tool handles that verification. The tie to null_prov_issuer also disambiguates it from other transparency tools.

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?

It gives clear operational guidance: keep the last seen head and expect later heads to extend it, with null_witness_range named as the extension-checking sibling. It does not explicitly enumerate when to use this tool versus null_transparency or null_prov_issuer, but the role is strongly implied.

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