Twelve Data MCP Server

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

With no annotations provided, the description carries the full burden of behavioral disclosure. It states the tool provides information, implying a read-only operation, but doesn't specify if it's safe (e.g., no side effects), requires authentication, has rate limits, or returns structured data. The description lacks details on response format, error handling, or any constraints beyond the basic purpose.

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 a single, straightforward sentence that efficiently states the tool's purpose without unnecessary words. It's front-loaded with the core function, making it easy to parse. However, it could be more structured by including key details, but as-is, it avoids verbosity.

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 complexity (1 parameter with nested properties), lack of annotations, and no output schema, the description is incomplete. It doesn't explain what the tool returns (e.g., usage metrics format), behavioral traits, or parameter interactions. For a tool that likely involves API key handling and data retrieval, more context is needed to guide effective use.

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 description has 0% schema description coverage, as it repeats the same text without explaining parameters. It doesn't add meaning beyond the input schema, which documents parameters like format, delimiter, timezone, outputsize, and apikey. For a tool with 1 parameter (a nested object with 5 sub-parameters), this is inadequate, failing to compensate for the low coverage.

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 states the tool 'will provide information on the current usage of Twelve Data API,' which clarifies it retrieves API usage data. However, it's vague about what specific usage metrics are returned (e.g., rate limits, quotas, historical data) and doesn't differentiate from siblings like GetStatistics or GetTechnicalIndicators, which might also provide data-related insights. The purpose is understandable but lacks specificity.

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?

No guidance is provided on when to use this tool versus alternatives. The description doesn't mention prerequisites (e.g., API key requirements), frequency of use, or comparisons to sibling tools like GetStatistics for general data or GetTimeSeries for time-based metrics. This leaves the agent without context for tool selection.

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