getTickersHistoricalById

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

The description explicitly states the tool is read-only, explains it returns point-in-time snapshots (not OHLC), and notes limitations like max 250 data points and plan requirement. No annotations provided, so description carries full burden and does it well.

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?

Well-structured with clear sections (purpose, usage, parameters, requirements). Each sentence adds value, no redundancy. Front-loaded with purpose.

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 no annotations, no output schema, and 6 parameters (2 required, 4 optional), the description covers all aspects: purpose, alternatives, parameter details with examples, defaults, limits, and API key requirement. Very thorough.

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?

Despite 100% schema coverage, the description adds critical context: explains coinId format with examples and warning against guessing, date formats, default values, and limit cap. This goes well beyond the schema descriptions.

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 states the tool retrieves historical point-in-time snapshots of price, market cap, and volume, and explicitly distinguishes from siblings like getCoinOHLCVHistorical (OHLC candles) and getTickersById (current price).

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?

Provides specific use cases ('price of BTC last Tuesday') and explicit alternatives for when not to use this tool (OHLC: getCoinOHLCVHistorical, current price: getTickersById). Also mentions read-only nature and plan requirement.

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