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

Annotations already provide readOnlyHint and idempotentHint; the description adds useful behavioral context by explicitly stating 'Pure function — no external calls, no ML' and detailing stop-word exclusion for the word frequency computation. This goes beyond the structured annotations and clarifies side-effect-free behavior without contradicting them.

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 description is a single compact sentence that front-loads the core purpose, lists concrete outputs, and ends with the pure-function guarantee. Every clause contributes useful information with no repetition or filler.

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?

For a single-parameter, pure, deterministic utility with an output schema and clear annotations, the description covers the essential behavior: what is computed, how stop words are handled, the hashing algorithm, and the absence of external dependencies. Nothing critical is missing for an agent to select and 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 coverage is 100% and the sole parameter 'text' is already well described in the schema, including arbitrary length and exact-input hashing. The tool description adds no new parameter-level meaning, so the baseline of 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?

The description states a clear operation ('deterministic text digest') and enumerates the exact outputs: word count, top-5 frequent words, first sentence, and keccak-256 hash. It is readily distinguishable from the sibling validation/lookup tools, though it does not explicitly name an alternative or contrast itself with one by name.

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?

The description implies usage: it is a pure, deterministic utility for text analysis and hashing, which is appropriate given the text input. However, it does not explicitly state when to use this tool versus alternatives or mention exclusions/limitations such as unsuitable text formats.

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