Databento MCP

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 mentions the tool 'returns the records as structured data', which hints at output behavior, but fails to address critical aspects like error handling (e.g., for invalid file paths), performance implications (e.g., for large files), or side effects (e.g., memory usage). For a read operation with zero annotation coverage, this leaves significant gaps in understanding how the tool behaves beyond its basic function.

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 front-loads the core functionality ('Read and parse a DBN file') and adds value with the outcome ('returning the records as structured data'). There is no wasted verbiage, repetition, or unnecessary details, making it highly concise and well-structured for its purpose.

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 tool has no annotations and no output schema, the description is incomplete for a data-reading tool with 3 parameters. It lacks details on output format (what 'structured data' means), error conditions, or performance considerations. While it states the basic purpose, it doesn't provide enough context for safe and effective use, especially compared to siblings like 'read_parquet_file' which might have different behaviors.

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 input schema has 100% description coverage, with clear documentation for 'file_path', 'limit', and 'offset'. The description adds no parameter-specific semantics beyond what's in the schema, such as explaining DBN file structure or record format. Since the schema does the heavy lifting, the baseline score of 3 is appropriate, as the description doesn't compensate but also doesn't detract.

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 ('Read and parse') and resource ('a DBN file'), specifying what the tool does. It distinguishes from siblings like 'convert_dbn_to_parquet' or 'write_dbn_file' by focusing on reading/parsing rather than conversion or writing. However, it doesn't explicitly differentiate from 'read_parquet_file' beyond file format, which is why it's not a perfect 5.

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 'read_parquet_file' for Parquet files or 'get_historical_data' for other data access methods. It lacks context about prerequisites (e.g., file availability) or exclusions, offering only a basic functional statement without usage context.

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