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

Even though readOnlyHint is true, the description adds substantial behavioral detail beyond annotations: the 81-character string format, 0-for-empty-cell encoding, included techniques and solve_url, difficulty givens ranges, technique-specific filtering, and error behavior when no puzzle matches. No contradiction with annotations exists.

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 description is well-organized and front-loaded, but it repeats the solve_url detail twice: 'response includes ... a solve_url' and later 'Every response includes a solve_url.' This redundancy makes it longer than necessary, though most sentences do add useful 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 no output schema, the description fully compensates by explaining the return format, puzzle encoding, difficulty options, technique filtering, error behavior, and alternative tools. An agent has enough information to select parameters and interpret the response correctly.

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. The description adds meaningful context beyond the schema by explaining what the technique parameter does, when it is useful, and how errors behave if no matching puzzle exists. It also enriches the difficulty parameter with concrete givens ranges.

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 opens with a specific verb and resource: 'Get a random sudoku puzzle from the PlaySudoku.us collection.' It also differentiates the tool from siblings by explicitly directing users to solve_sudoku for full solutions and explain_next_step for hints.

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 description provides clear guidance on when to use this tool versus alternatives: 'Use solve_sudoku for a full step-by-step solution, or explain_next_step to get one hint at a time.' It also gives a concrete use case for the optional technique parameter, such as practicing 'X-Wing' or 'Hidden Pair'.

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