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

Annotations already cover the safety profile (readOnly, non-destructive, closed-world). The description goes beyond them by disclosing the return contents (SHA-256 fingerprint and match verdict) and two important limitations: it does not store the text and does not prove when it was written, which steers the agent away from misuse as a timestamping tool.

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 tight sentences with zero filler, ordered by importance: when to use, what it returns, and what it does not do. Every sentence 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?

Although there is no output schema, the description fully explains the return values (fingerprint and match result) and the tool's boundaries. With both parameters documented and low tool complexity, an agent has everything needed to invoke it 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?

Schema description coverage is 100%, so the schema already documents both 'text' and 'expected' (including the 64-hex-character constraint). The description only restates that a match is returned when an expected fingerprint is supplied, adding marginal meaning over 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?

States a specific verb (fingerprint) and resource (a piece of text) and precisely what it returns: the SHA-256 fingerprint plus an optional match result. The function is unambiguous and easily distinguished from the unrelated siblings request_service and world_now.

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?

Front-loads the trigger condition clearly: 'Use when the user wants to know whether two texts are exactly identical, or wants a fingerprint to compare a document against later.' It also implicitly frames a when-not (proving timestamps/provenance). No alternative tool is named, but the siblings are not viable substitutes, so this is close to complete.

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