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

With no annotations, the description carries the full burden. It discloses critical behavioral traits: data is sha256-committed before outcomes were known, append-only, never revised, and costs $0.02 USDC per call. This provides transparency about data integrity, mutation policy, and pricing beyond the basic tool name.

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 compact, using three sentences to convey purpose, integrity guarantees, usage variation, and pricing. It front-loads the core value proposition ('Point-in-time archive') and avoids redundancy; every sentence earns its place.

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?

Given the tool's simplicity (one optional parameter, no output schema), the description is complete. It covers the purpose, the historical/provenance use case, the append-only behavior, the cost, and the variation when omitting the date. It does not explain the return format, but that's not necessary given the tool's straightforward nature.

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?

The schema already provides 100% coverage of the single 'date' parameter, describing it as an archived date in YYYY-MM-DD format and noting it can be omitted for the archive index. The tool description repeats this usage ('omit date for the list of archived dates') without adding new semantics, so a baseline score of 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?

The description clearly identifies the tool as a point-in-time archive of Coil's published scores for a specific archived date, distinguishing it from live/free counterparts by emphasizing sha256-committed, append-only data and backtest-grade provenance. This specific verb+resource+scope definition differentiates it from sibling tools like get_full_board.

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 context: it is for backtest-grade historical data, explicitly noting 'no free counterpart' and instructing to 'omit date for the list of archived dates.' It implies use for archival/provenance needs rather than live data, though it doesn't name explicit alternative tools.

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