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

Annotations already declare readOnlyHint, idempotentHint, openWorldHint=false, and destructiveHint=false, so the safety profile is covered. The description adds useful beyond-annotation context: determinism ('same input gives same output') and concrete limits (64 KB JSON input, 1 s per call, 1 MB result). It could say more about output shape, but an output schema exists.

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 content is front-loaded and organized with clear labels for usage, exclusions, side effects, determinism, and limits. However, the full Spanish and English versions duplicate the same information, so the description is longer than strictly necessary for an agent.

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?

Given a simple 3-parameter tool with full schema coverage, rich annotations, and an output schema, the description covers everything an agent needs: exact scope, alternative tool, determinism, side effects, and hard limits. No important behavioral or usage gap remains.

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 n, r, and repetition are already fully documented with types, bounds, default, and examples. The description adds only the n ≤ 10,000 scope and the phrase 'with or without repetition', which is marginal beyond the schema. Baseline 3 is appropriate when the schema carries parameter meaning.

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 exact nCr and nPr with or without repetition for n ≤ 10,000. It clearly distinguishes itself from the sibling bigint-calc by scope, so an agent can tell which tool handles combinatorics versus general arbitrary-precision arithmetic.

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?

Explicitly says when to use it ('a numeric result has to be exact or reproducible instead of estimated') and when not to use it ('Not for: computing the exact arbitrary-precision integer arithmetic (bigint-calc)'). The alternative sibling is named directly, leaving little inference required.

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