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

Annotations already declare readOnlyHint=true and openWorldHint=false, so the safety profile is covered. The description nonetheless adds real context the annotations cannot: the licensing/provenance of the data (Dolch 1936, public domain) and the fact that limits are disclosed rather than hidden. It does not describe the response shape, but as a static no-argument explainer that is a minor gap.

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 compact sentences, front-loaded with the core purpose and with the source list immediately after. The trailing fragment 'Includes the limits.' is terse to the point of slight ambiguity about what those limits are, which costs a point but no text 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?

With no parameters, no output schema, and simple read-only annotations, the description covers everything an agent needs to decide to call it. The only shortfall is that it does not say whether this returns a per-word basis or a single document-level explanation, which affects how an agent would use the result.

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?

The tool takes zero parameters, so there is nothing for the description to disambiguate; baseline is 4. The description correctly does not waste words restating empty schema content.

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: it explains the provenance of each grade placement, and enumerates the three possible sources (Dolch 1936, Common Core Foundational Skills, typical sequence). It does not explicitly position itself against the sibling get_citation, which is the most plausible source of confusion, so it stops short of a 5.

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?

There is no explicit 'use this when' or 'do not use' statement, but the content strongly implies the use case: understanding why a word was assigned a grade and what the methodology's limits are. The absence of any routing against get_citation or get_words_for_grade keeps it at implied rather than stated guidance.

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