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

Beyond the annotations (readOnly, idempotent), the description adds substantial behavioral detail: determinism, exact output components, stop-word exclusion, and the specific hash algorithm keccak-256. It also explicitly rules out external calls and ML, giving the agent a precise model of the tool's behavior.

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?

Two tightly packed sentences, no filler or redundancy. The most important information (outputs and determinism) is front-loaded, and the functional nature of the tool is stated immediately.

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?

The description fully covers the tool's behavior for a single-parameter pure function with an output schema present. It tells the agent what results to expect, the deterministic nature, the absence of side effects, and the hashing algorithm, leaving no meaningful gap for correct invocation.

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%, including the note about arbitrary length and hashing over the exact input, so the tool description does not need to add parameter-level detail. The description contributes no additional parameter semantics but also does not need to, given the schema already fully documents the single 'text' parameter.

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 specific action and resource: 'Deterministic text digest' followed by exactly what it produces — word count, top-5 frequent words, first sentence, and keccak-256 hash. This clearly differentiates it from the sibling validation/check tools by emphasizing pure local computation rather than external lookups.

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 gives a clear context for when to use the tool: any time a deterministic local text summary is needed. It does not explicitly name alternatives, but the explicit statement 'Pure function — no external calls, no ML' establishes that this is the appropriate choice for offline text analysis, and no sibling tool competes for that role.

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