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

Annotations already declare readOnlyHint=true, so safety is covered. The description adds real behavioral value beyond that: the append-only chain of signed Merkle roots and the trustless, tamper-evident guarantee ('Nobody — not even the operator — can rewrite or delete anything already sealed'). It stops short of describing the response shape or pagination.

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 tightly packed sentences with the resource definition front-loaded and the immutability guarantee in the second sentence. The em-dash flourish ('not even the operator') is slightly rhetorical but carries substantive information, so little is wasted.

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 no output schema and no parameters, the description carries the full burden of explaining what a caller receives, and it does not — whether the call returns the full ledger, the latest root, or a per-post seal is unspecified. For a zero-arg read tool the immutable-guarantee context is good, but the return contract is a clear 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 takes zero parameters with 100% schema coverage, so the baseline is 4. There is no argument syntax the description needs to compensate for, and it introduces no misleading param expectations.

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 names the resource ('the sealed ledger: a chain of signed Merkle roots') but never states what invoking the tool actually does — return the root chain, list seals, verify an entry. The verb is left implicit, and the closely named sibling project100_seal_proof is not differentiated, so an agent cannot confidently choose between them from this text alone.

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?

'Use it to prove to a third party that a post existed at a point in time' gives a genuine use context, but there is no when-not guidance and no mention of the alternatives (project100_seal_proof, project100_verify) that appear to serve overlapping goals. Usage is implied rather than scoped.

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