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

Annotations already declare readOnlyHint, idempotentHint, openWorldHint, and destructiveHint=false. The description adds useful behavior beyond those annotations by stating the boolean return value and the one-credit cost, though it does not describe handling of malformed boards or the string representation allowed by the schema.

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 front-loaded and compact: purpose, validation rules, return behavior, and cost appear in three short sentences. There is no unnecessary repetition or filler.

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 one-parameter validation tool with rich annotations and full schema coverage, the definition is nearly complete. The main remaining gap is that malformed-board handling and the exact string board format are not clarified, but the boolean return and cost are covered.

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 the single board parameter is already documented in the schema. The description only repeats that the input is a 9x9 board and does not clarify the schema's anyOf choice between a 2D string array and a string representation, so it adds little parameter meaning beyond the schema.

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 uses a specific verb and resource: checks whether a 9x9 Sudoku board is valid. It also names the exact validation rules—rows, columns, and 3x3 sub-grids must contain no duplicate digits 1-9—so the agent can distinguish this from generic calculation or puzzle tools.

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 usage is implied by the name and the validation rules, but there is no explicit when-to-use or when-not-to-use guidance. No alternatives or prerequisites are named, which is acceptable for a narrow utility but leaves usage context implicit.

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