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

Annotations already declare readOnlyHint=true, idempotentHint=true, openWorldHint=false and destructiveHint=false, so the safety profile is covered. The description still adds real value beyond them: determinism, no network/stored state, and concrete limits (64 KB input, 1 s per call, 1 MB result). Minor deduction because the stated 64 KB input cap conflicts with the schema's 1 MB maxLength on `data`.

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?

Each sentence is labeled (When / Not for / Side effects / Deterministic / Limits) and the core purpose is front-loaded. The full Spanish and English duplication roughly doubles the length, which is the main cost to 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?

An output schema exists, so return values need not be described, and the description covers side effects, determinism and rate/volume limits. The only gap is the conflicting input-size bound (64 KB in prose vs. 1 MB in the schema), which could mislead an agent on large inputs.

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 both `data` and `input_encoding` (with its utf8/hex/base64 enum) are already documented in the schema. The description adds no parameter-level meaning beyond that, so baseline 3 applies.

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 and resource ('Computes the FNV-1a 32-bit hash') and explicitly names the sibling it is not (checksum-fnv1a64), so an agent can distinguish it from the many other hash/checksum tools without opening schemas.

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?

Gives an explicit 'When' clause (fast non-cryptographic checksum for error detection, sharding, hash tables) and an explicit 'Not for' clause pointing to checksum-fnv1a64. Both the positive and negative routing conditions are spelled out.

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