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

Annotations already declare readOnly, idempotent, non-destructive and closed-world, so safety is covered. The description adds genuine context the annotations cannot express: this is a legacy alias retained for cards opened before a rename. It says nothing, however, about what a call returns or how wrong guesses behave, and with no output schema that silence matters.

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?

One compact sentence with the most decision-relevant clause ('never by the model') front-loaded. No padding or repetition. It is short to the point of omitting useful detail, but nothing in it is wasted.

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 6-parameter tool with no output schema, the definition covers only the compatibility status; it never explains what comes back (correct/incorrect, remaining attempts, updated board state). Since the model is told not to use it, the gap is tolerable, but an agent that does encounter it lacks enough to interpret results.

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%, so every parameter including guess, puzzle_number, time_zone, previous_guesses and conversation_id is already documented in the schema. The description adds no parameter meaning whatsoever, which is acceptable here but earns only the baseline.

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 identifies the tool as an earlier name for 'this puzzle step' kept for backward compatibility, which implies it duplicates the guess-checking sibling, but it never states the function directly (submit a word guess and get correctness feedback). The title 'Check a guess' carries most of the actual purpose, so the description alone is vague on what a call does.

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?

Strong, explicit exclusion: 'Used only by the puzzle card, never by the model.' That is a clear when-not-to-use rule an agent can act on immediately. It falls short of a 5 because it never names the replacement it should call instead (weather_word_puzzle_guess), leaving the routing implicit.

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