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

Annotations already declare readOnlyHint=true, openWorldHint=false, idempotentHint=true, and destructiveHint=false. The description adds useful context such as no network access, no stored state, determinism, and limits, but its stated limits conflict with the schema: input up to 64 KB versus schema maxLength 1 MB, and result up to 1 MB versus output_bytes max 1024. The added behavioral detail is therefore helpful but partly inaccurate.

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?

The purpose and when/when-not guidance are front-loaded and clearly labeled, so the structure is strong. However, the entire description is duplicated in Spanish and English, roughly doubling length without adding new information, which weakens conciseness.

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 full schema coverage, an output schema, and rich annotations, the description supplies enough context to select and invoke the tool correctly. The inaccurate size limits prevent a top score, but the core purpose, usage guidance, and side-effect profile are present.

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 parameter names, defaults, enums, and bounds are already fully documented. The description mentions chosen output length of 1 to 1024 bytes and text-or-bytes input, but adds little beyond what the schema already provides. Baseline 3 is appropriate when the schema does the heavy lifting.

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 SHAKE128, cites FIPS 202, and states that it computes an extendable-output digest with a chosen output length. It explicitly distinguishes itself from the sibling hash-shake256, so an agent can identify the operation without opening the schema.

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 states when to use the tool: when an exact digest of text or bytes is needed, for example to compare content or match a published checksum. It also states when not to use it and names the alternative, hash-shake256, giving explicit routing guidance.

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