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

Annotations already declare readOnlyHint=true and destructiveHint=false, so the safety profile is covered. The description adds two genuinely non-obvious behavioral facts: category filtering only works on paid plans, and each call costs 1 credit. It stops short of saying what happens if a category is requested on a free plan (error vs. silent fallback to random).

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?

A single dense sentence that front-loads the purpose and appends cost in parentheses. The only waste is the redundant prefix repeating the tool name verbatim before the colon, which adds no information.

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 an output schema present and only four optional parameters, the return-value burden is lifted and the description covers purpose, difficulty semantics, plan gating, and cost. The remaining gap is behavioral: it does not specify the free-plan fallback for category, nor acknowledge the image-generation capability, which is a meaningful output mode for a puzzle tool.

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 coverage is 100%, so the baseline is 3, but the description meaningfully enriches two parameters: difficulty is explained as being derived from word length, and category is constrained by plan tier. The image parameter is not mentioned at all in the description, which keeps it from a 5.

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+resource (provides random hangman words) and adds two distinguishing traits: difficulty keyed to word length, and category filtering gated to paid plans. It does not, however, differentiate itself from near-neighbors such as RandomWord, WordScrambleGenerator, or SpellingBeeGenerator, which occupy adjacent space.

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 phrase 'for word games' implies the usage context, but there is no explicit when-to-use or when-not-to-use guidance and no named alternative among the many word/puzzle siblings. The agent must infer that this is the hangman-specific option rather than a generic word source.

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