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

Annotations already declare readOnly/idempotent/openWorld=false, and the description still adds value: no network, no stored state, deterministic output, plus runtime limits (1 s per call, up to 1 MB result). However the stated '64 KB' input limit conflicts with the schema's maxLength of 1048576 (1 MB), which could mislead an agent about acceptable input size.

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?

Purpose is front-loaded and each language block is internally tight with zero filler. The full content is duplicated in Spanish and English, which doubles length without adding information for a given agent, though it matches the multilingual pattern of this tool set.

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 read-only annotations, an output schema, and fully documented params, the description carries its remaining burden well by adding determinism and limit context. The 64 KB vs 1 MB maxLength discrepancy is the one thing that could cause a misjudged call.

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 both enums are documented in the schema, so baseline 3 applies. The description adds only that no key is used; it never mentions input_encoding/output_encoding or encoding semantics beyond what the schema already says.

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 (computes), resource (BLAKE2b digest, 512-bit output, RFC 7693) and a qualifying property (unkeyed), which pins down the algorithm among ~30 hash siblings. An agent can distinguish it from hash-blake2s256 or hash-sha512 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?

Explicit 'When' clause gives concrete triggers (comparing content, matching a published checksum) and an explicit 'Not for' that names the alternative tool (hash-sha512). Both the use case and the exclusion are spelled out rather than inferred.

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