Daily historical weather for a point/date range via Open-Meteo's ERA5-based archive (no key, free, data back to 1940). Dates are YYYY-MM-DD. Returns JSON: {ok, daily: {time, ...}, source}.
| Name | Required | Description | Default |
|---|---|---|---|
| lat | Yes | ||
| lon | Yes | ||
| end_date | Yes | ||
| variables | No | temperature_2m_mean,precipitation_sum | |
| start_date | Yes |
| Name | Required | Description | Default |
|---|---|---|---|
| result | Yes |
Changes observed during successful MCP inspections.
Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?
No annotations are provided, so the description must fully disclose behavior. It explains the data source, date format, that it's free and keyless, and the return JSON structure. It does not describe error handling, rate limits, or geographic coverage limitations, but the provided information is sufficient for basic use.
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 two sentences: the first states the purpose and key differentiator, the second covers dates and return format. Every word adds value, and the structure is front-loaded for quick understanding.
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?
With 5 parameters and no annotations, the description covers the essential behavioral aspects and output format. It lacks some edge-case details (e.g., historical range before 1940, invalid coordinates) but is adequate for a free API tool. The presence of an output schema helps, though the description already summarizes it.
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 0%, yet the description only explains the date format (YYYY-MM-DD) for start_date and end_date. It does not clarify lat/lon conventions, the 'variables' parameter format (comma-separated), or other parameter defaults/ranges. This is a significant gap given the lack of schema descriptions.
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 specifies the tool provides daily historical weather data for a point/date range via Open-Meteo's ERA5 archive. It distinguishes itself from sibling tools (all geospatial analysis) by focusing on climate history.
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 mentions it is free and requires no API key, which are useful usage guidelines. However, it does not explicitly state when to use this tool versus alternatives, nor does it provide any exclusion criteria. Given that siblings are all different, it's implicitly the only weather tool, but explicit guidance is missing.
Agents often have multiple tools that could apply. Explicit usage guidance like "use X instead of Y when Z" prevents misuse.
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