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

Annotations already declare readOnlyHint=true, so the safety profile is covered. The description adds genuine context beyond that: the digest is recomputed server-side on the spot, a mismatch is reported in the response, and the result does not require trusting the server because the agent can recompute itself. It stops short of describing the full response shape.

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 short sentences with no padding, and the core action (recomputed digest) is front-loaded. The opening fragment 'One stone, with its digest recomputed on the spot.' is slightly telegraphic but still earns its place by scoping the operation to a single stone.

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 single-parameter, read-only tool with no output schema, the description covers the essential behavior: what is computed, that a mismatch is reported, and the trust model. It could say more about what a matching response returns, but nothing critical for correct invocation is missing.

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 there is a single parameter with a clear schema description ('Stone id from project100_stones, e.g. stn_000001'). The description references the canonical text and stored digest, but adds no syntax or format detail for stone_id beyond the schema. Baseline 3 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 action: fetch one stone and recompute its sha256 digest over the canonical text for comparison. It is clear what the tool does, though it never names or distinguishes itself from close siblings like project100_stones (listing) or project100_verify (general verification).

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?

Usage is implied by the verification workflow it describes (recompute and compare), so an agent can infer this is for independently checking a stone's integrity. However, there is no explicit 'use this when... instead of project100_stones/project100_verify' guidance or any stated prerequisite/exclusion.

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