Open-Meteo MCP Server

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

No annotations are provided, so the description carries the full burden of behavioral disclosure. While it mentions 'high-quality global forecasts,' it doesn't describe critical behavioral aspects: whether this is a read-only operation, rate limits, authentication requirements, data freshness, error conditions, or what the output format looks like. For a complex 11-parameter tool with no annotations, this is a significant gap in behavioral transparency.

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 gets straight to the point: 'Get weather forecast from European Centre for Medium-Range Weather Forecasts with high-quality global forecasts.' Every word earns its place - it specifies the action, source, and quality without any fluff or redundancy.

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 (11 parameters, no output schema, no annotations), the description is insufficiently complete. It doesn't explain what the tool returns, how forecasts are structured, time ranges covered, data resolution, or any limitations. For a weather forecast tool with numerous configuration options and no output schema, users need more context about what to expect from the response.

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 the schema already documents all 11 parameters thoroughly with descriptions, ranges, enums, and defaults. The description doesn't add any parameter-specific information beyond what's in the schema. According to scoring rules, when schema_description_coverage is high (>80%), the baseline is 3 even with no param info in the description.

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: 'Get weather forecast from European Centre for Medium-Range Weather Forecasts with high-quality global forecasts.' It specifies the action ('Get weather forecast'), the source (ECMWF), and a quality characteristic. However, it doesn't explicitly differentiate from sibling tools like 'weather_forecast' or 'gfs_forecast' that might offer similar functionality from different sources.

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. With multiple sibling tools offering weather forecasts (e.g., 'weather_forecast', 'gfs_forecast', 'metno_forecast'), there's no indication of what makes ECMWF forecasts unique or when they should be preferred. The description mentions 'high-quality global forecasts' but doesn't explain how this compares to other forecast sources.

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