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 and determinism profile is fully covered. The description adds that results are broken down 'letter by letter' and include common/rare classification, but since an output schema exists, this return-value detail is largely duplicated structured data, and no auth, rate-limit, or edge-case behavior (e.g. invalid characters) is disclosed.

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 with no filler: the action is front-loaded and the return content follows immediately. Every clause ('valid', 'common or rare', 'Scrabble and Words With Friends points') carries information an agent would otherwise have to dig for.

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 simple two-parameter, read-only lookup tool with full schema coverage, an output schema, and rich annotations, the description covers purpose and outcome categories adequately. Minor gap: it doesn't say what happens with edge inputs (too short, non-alphabetic) or that 'scoring' defaults to scrabble, though the schema supplies the default.

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% — both the 'word' parameter and the 'scoring' enum are documented in the schema with the default noted. The description echoes the two scoring systems and the letter-by-letter output but adds no syntax, format rules, or constraint detail beyond what the schema already states, so baseline 3 applies.

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 verb and resource ('Checks a word against the dictionary and scores it') and enumerates the three outputs: validity, common/rare status, and Scrabble/WWF points. That scope is unmistakably distinct from the sibling tools (word_list, find_anagrams, solve_pattern, solve_wordle, unscramble_letters), none of which score a single word.

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?

Usage is only implied by the phrasing 'Checks a word' — an agent can infer this is the tool for validating or scoring one specific word. There is no explicit when-to-use statement and no exclusion pointing to alternatives such as find_anagrams when the agent has letters rather than a word.

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