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 returns an array and that the list is updated daily, but it doesn't cover critical aspects like whether this is a read-only operation, potential rate limits, authentication requirements (implied by the 'apikey' parameter but not stated), error handling, or pagination. For a tool with multiple parameters and no annotation coverage, this leaves significant gaps in understanding its behavior.

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 concise and front-loaded, consisting of two clear sentences that state the core functionality and update frequency. There is no unnecessary verbosity, and every sentence adds value (though limited). However, it could be more structured by explicitly mentioning key parameters or usage scenarios.

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 (8 parameters, no annotations, no output schema), the description is incomplete. It lacks details on parameter usage, behavioral traits like authentication or rate limits, and output format. The daily update note is helpful but insufficient for a tool with this level of parameter richness and no structured support from annotations or output schema.

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 adds no parameter semantics beyond what the input schema provides. With a schema description coverage of 0% (the schema's description is identical to the tool description), the description fails to explain any of the 8 parameters (e.g., 'symbol', 'exchange', 'outputsize') or their purposes. This is inadequate given the low schema coverage and multiple parameters.

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: 'returns an array of cryptocurrencies available at Twelve Data API.' It specifies the verb ('returns') and resource ('cryptocurrencies'), and mentions the data source. However, it doesn't explicitly differentiate from sibling tools like 'GetStocks' or 'GetForexPairs' beyond the resource name, which is why it doesn't reach a perfect score.

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 no guidance on when to use this tool versus alternatives. It doesn't mention any prerequisites, such as needing an API key, or compare it to related tools like 'GetCryptocurrencyExchanges' or 'GetSymbolSearch'. The only contextual note is that the list is updated daily, which is minimal usage information.

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