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

Annotations already cover the safety profile (readOnly, idempotent, non-destructive, closed-world), so the bar is lower. The description still adds genuinely useful behavior not in annotations: the fallback when today's puzzle is unpublished ('the latest one is returned: check date') and the SAN move-ordering convention. No auth or rate-limit context is given, keeping it short of a 5.

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?

Front-loads the core purpose, then constraints, then return-format notes; each sentence carries information. Slightly dense and the trailing playUrl sentence is useful but secondary, so not a flawless 5.

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 not be described, yet the description still explains the returned position (fen with solver to move), the SAN solution ordering, and the fallback date behavior. For a single-optional-parameter read tool, nothing needed to invoke it correctly is missing.

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% and the schema already documents the date pattern and its valid range, so the description's restatement of the YYYY-MM-DD format and 2024-01-01-to-today range adds little. Baseline 3 is appropriate when the schema does the heavy lifting.

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 and resource ('Get Chessigma's daily chess puzzle') with explicit scope (today by default, past days via date). It is unmistakably distinct from the sibling analysis tools (analyze_game, analyze_position, etc.), which operate on user-supplied games rather than a curated daily puzzle.

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?

Gives clear conditional usage: omit date for today, pass date for a past day, and an explicit behavioral constraint ('Do not reveal the solution unless the user asks for it'). It does not name alternative tools or when-not-to-use, so it falls short of the 5-level routing guidance.

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