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. It states what the tool returns (metadata including symbology mappings and instrument definitions) but doesn't describe important behavioral aspects like whether this is a read-only operation, potential rate limits, authentication requirements, error conditions, or response format. For a tool with 4 parameters and no annotation coverage, this leaves significant gaps in understanding how the tool behaves.

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 states the core purpose without unnecessary words. It's appropriately sized for a metadata retrieval tool. However, it could be slightly more front-loaded by explicitly mentioning it's for retrieving symbol metadata rather than just 'Get metadata for symbols' which could be ambiguous.

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 4 parameters, no annotations, and no output schema, the description is incomplete. It doesn't explain what format the metadata returns in, whether there are pagination considerations, error handling, or performance characteristics. The description alone is insufficient for an agent to understand the full context of using this tool effectively, especially given the lack of structured behavioral information elsewhere.

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 description coverage is 100%, so all parameters are documented in the schema. The description adds no additional parameter information beyond what's already in the schema. It doesn't explain relationships between parameters or provide examples of valid symbol formats. With complete schema coverage, the baseline score of 3 is appropriate as the description doesn't enhance parameter understanding but doesn't need to compensate for schema gaps.

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 verb 'Get' and the resource 'metadata for symbols', specifying it includes 'symbology mappings and instrument definitions'. This distinguishes it from siblings like 'get_historical_data' or 'get_live_data' which focus on data retrieval rather than metadata. However, it doesn't explicitly differentiate from 'resolve_symbols' or 'search_instruments' which might have overlapping functionality.

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 'resolve_symbols' or 'search_instruments'. It doesn't mention prerequisites, use cases, or exclusions. The agent must infer usage from the tool name and parameters alone, which is insufficient 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.