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

Annotations already declare readOnlyHint=true, idempotentHint=true, destructiveHint=false and openWorldHint=false, so the safety profile is fully covered without the description's help. The description adds the nature of the analysis (variant forms, frequency, per-decade normalization), but that is largely return-value content already carried by the output schema, and it discloses nothing about cost, limits, or query semantics.

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 purpose and both output dimensions are front-loaded in the first sentence, with usage in the second. The framing phrase 'Come una parola compare davvero nei giornali' is slightly decorative but earns its place as orientation, and nothing is redundant.

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 re-specified, and the description nonetheless sketches them. Purpose, use case, and call granularity are all present; the only real omission is what exactly constitutes a valid 'parola' argument, which matters given the 0% parameter coverage.

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?

With one parameter at 0% schema description coverage, the description must carry the load, and it partially does: 'una alla volta' establishes that the input is a single word, and the inline examples ('vajuolo', 'vaiolo', 'inondazione', 'piena') show the expected value form. However, it never states whether the input must be a bare form, whether case/diacritics matter, or whether lemmas are accepted.

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 names a specific operation (surfacing the actual forms a word takes in the archive) and enumerates the two outputs it produces: spelling/OCR variants with frequency, and per-decade usage normalized per million printed words. This is clearly distinct from sibling tools like search or read_passages, which retrieve documents rather than analyze lexical forms.

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?

It states a concrete use case — picking era-appropriate search terms ('vajuolo' vs 'vaiolo', 'inondazione', 'piena') and gauging when a theme peaks — and adds the operational constraint 'una alla volta' (one word per call). It stops short of explicitly naming which sibling to run afterward (e.g., search), so it is clear context without an explicit alternative-naming.

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