Historical price series for a coin. days = lookback in days (1, 7, 14, 30, 90, 180, 365, 'max'). interval may be 'daily' or 'hourly' (free tier daily-only beyond 90 days).
| Name | Required | Description | Default |
|---|---|---|---|
| id | Yes | ||
| vs | No | usd | |
| days | No | ||
| interval | No |
Changes observed during successful MCP inspections.
Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?
No annotations provided, but description explains API tier constraint and parameter behavior. Does not disclose rate limits or authentication, but sufficient for basic usage.
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?
Two sentences, front-loaded with core purpose, no extraneous text. Efficient and clear.
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?
Explains days and interval in detail, but omits explanation for id (required) and vs. No output schema description, leaving return format unspecified.
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 0% schema coverage, explains days and interval meaningfully. However, id and vs remain unexplained; days schema says integer but description allows 'max' (potential contradiction).
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?
Clearly states 'Historical price series for a coin', specifying the action and resource. Differentiates from siblings like crypto_prices (current prices) and crypto_search.
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 parameter constraints (allowed days values, interval options, free tier limitation). Lacks explicit when-to-use or when-not-to-use compared to siblings.
Agents often have multiple tools that could apply. Explicit usage guidance like "use X instead of Y when Z" prevents misuse.
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