Open-Meteo 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 data source (ERA5 reanalysis) and temporal range (1940-present), but lacks critical details such as rate limits, authentication needs, data format, error handling, or whether it's a read-only operation. For a tool with 8 parameters and no output schema, this is a significant gap.

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 purpose without unnecessary words. Every element ('Get historical weather data,' 'ERA5 reanalysis,' '1940-present,' 'specific coordinates and date range') contributes directly to understanding the tool's function.

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's complexity (8 parameters, no annotations, no output schema), the description is incomplete. It doesn't address behavioral aspects like data retrieval limits, response format, or error conditions, nor does it provide usage guidelines relative to siblings. For a historical data tool with rich parameters, more context is needed to ensure effective agent 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 adds minimal parameter semantics beyond the schema, which has high coverage (88%). It mentions 'coordinates and date range,' aligning with the required parameters (latitude, longitude, start_date, end_date), but doesn't explain the hourly/daily arrays or optional parameters like temperature_unit. Baseline 3 is appropriate given the schema's thorough documentation.

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 ('Get historical weather data') and resource ('from ERA5 reanalysis'), with specific scope ('1940-present') and constraints ('for specific coordinates and date range'). It distinguishes from forecast-oriented siblings like 'weather_forecast' by emphasizing historical data, though it doesn't explicitly name alternatives.

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 explicit guidance on when to use this tool versus alternatives is provided. While the description implies historical data retrieval, it doesn't mention when to choose this over other weather tools (e.g., 'climate_projection' for future scenarios or 'weather_forecast' for predictions), nor does it discuss prerequisites or exclusions.

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