OpenWeatherMap 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. It mentions the forecast duration ('up to 5 days') but doesn't cover other important aspects like rate limits, authentication requirements, error handling, or what the forecast includes (e.g., temperature, precipitation). For a tool with no annotation coverage, this leaves significant gaps in understanding its behavior.

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, clear sentence that efficiently conveys the core functionality without unnecessary words. It's front-loaded with the main purpose and appropriately sized for the tool's complexity. Every part of the sentence earns its place by specifying key constraints.

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 lack of annotations and output schema, the description is insufficiently complete. It doesn't explain what the forecast returns (e.g., data structure, time intervals), potential limitations, or how it differs from sibling tools. For a weather forecasting tool with multiple similar alternatives, more context is needed to help the agent use it correctly.

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 doesn't add any parameter-specific information beyond what's already in the input schema, which has 100% coverage. It mentions 'up to 5 days', which aligns with the 'days' parameter's description in the schema, but provides no additional context about parameter interactions or usage examples. With high schema coverage, the baseline score of 3 is appropriate.

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 for up to 5 days'. It specifies the verb ('Get'), resource ('weather forecast'), and scope ('up to 5 days'), making it easy to understand. However, it doesn't explicitly differentiate from siblings like 'get-daily-forecast' or 'get-hourly-forecast', 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. With siblings like 'get-daily-forecast', 'get-hourly-forecast', and 'get-current-weather', the agent is left to infer usage based on tool names alone. No explicit when/when-not statements or alternative recommendations are included.

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