Databento MCP

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

With no annotations provided, the description carries full burden for behavioral disclosure but offers minimal information. It doesn't mention whether this is a read-only or write operation (though 'write' implies mutation), what permissions are required, whether it's idempotent, or how errors are handled. For a tool that writes files, this is a significant gap in behavioral context.

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, efficient sentence that communicates the core functionality without unnecessary words. It's appropriately sized for the tool's complexity and gets straight to the point with zero wasted verbiage.

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?

For a tool with 7 parameters that writes files (implying mutation and side effects), the description is inadequate. With no annotations, no output schema, and minimal behavioral context, the agent lacks crucial information about what this tool actually does, what it returns, and how it behaves in different scenarios.

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 doesn't add any parameter-specific information beyond what's already documented in the input schema (which has 100% coverage). It doesn't explain relationships between parameters, provide examples of valid combinations, or clarify edge cases. With complete schema coverage, the baseline of 3 is appropriate.

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 action ('write') and resource ('historical data query results to a DBN file'), making the purpose immediately understandable. However, it doesn't explicitly differentiate from sibling tools like 'export_to_parquet' or 'convert_dbn_to_parquet', which would require more specific comparison.

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 like 'export_to_parquet' or 'get_historical_data'. There's no mention of prerequisites, performance considerations, or typical use cases, leaving the agent with insufficient context for optimal tool selection.

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