get_historical_prices

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

Despite having no annotations, the description fully discloses behavioral traits: returns ordered [timestamp_ms, price] pairs, automatic granularity adjustment based on days, retry with 5-second backoff on rate limits, and accepts common symbols or CoinGecko IDs. No contradictions with annotations.

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 well-structured and concise: front-loaded with purpose, followed by output format, use cases, granularity details, usage guidance, and fallback behavior. Every sentence provides necessary information without redundancy.

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 and an output schema present, the description covers all critical aspects: purpose, parameters, behavior, error handling (retry), and differentiation from siblings. It is sufficiently detailed for correct tool invocation.

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 0%, but the description compensates by explaining the days parameter's effect on granularity (5-min, hourly, daily), default value (7), valid range, and that symbol accepts common symbols or CoinGecko IDs. It does not detail the currency parameter beyond default, but adds substantial meaning overall.

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's purpose: retrieving historical price data for a cryptocurrency over a specified number of days. It distinguishes itself from sibling tools by explicitly contrasting with get_price for single current prices and mentioning use cases like charting and backtesting.

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 explicit guidance on when to use this tool ('when you need a price series rather than a single current price') and points to the sibling tool get_price as the alternative. Also specifies valid range (1-365 days) and data granularity variations, enabling correct decision-making.

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