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

Annotations already declare readOnlyHint=true and openWorldHint=true, but the description adds genuinely new behavior: user identity fields are stripped from the response, requests are serialized, and a 429 requires a 60-second wait. These are exactly the operational details an agent cannot get from the annotations and would otherwise discover by failing.

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?

Three dense sentences with no filler, front-loaded with the core purpose followed by parameter values and then operational constraints. Minor cost: the difficulty and color enumerations duplicate the schema verbatim, spending words that could have gone to sibling disambiguation.

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?

An output schema exists, so return values need no explanation, and all params are covered. The remaining gap is the 'next' semantics: the description never states whether each call advances a sequence, returns a fresh random puzzle, or repeats the same puzzle, which is the key behavior for a tool named 'next'.

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 schema already documents all three parameters and their allowed values; the description largely restates them. Its only marginal addition is framing angle as open text, which the schema also states ('does not publish a closed theme enum'). Baseline 3 is appropriate.

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?

Opens with a specific verb and resource ("Returns a public Lichess puzzle") and characterizes the puzzle as public/anonymous, which is more than a restatement of the name. It does not, however, distinguish this from siblings such as lichess_puzzle, lichess_puzzle_daily, or lichess_puzzle_batch, leaving the agent to infer why 'next' exists.

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 lists what the optional filters accept and gives a retry rule for HTTP 429, but says nothing about when to choose this tool over lichess_puzzle, lichess_puzzle_daily, or lichess_puzzle_many. There are no exclusions or selection conditions, so invocation choice rests entirely on the tool name.

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