MCP Weather Server

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

With no annotations provided, the description carries full burden for behavioral disclosure. It states this is a 'Get' operation (implying read-only) and describes the return format, but doesn't mention authentication needs, rate limits, error conditions, or whether the forecast data is cached/live. For a weather API tool with zero annotation coverage, this leaves significant behavioral gaps.

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 efficiently structured with a clear purpose statement followed by Args and Returns sections. Each sentence adds value, though the 'Returns' section could be slightly more detailed given the output schema exists. Overall, it's appropriately sized and front-loaded.

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 moderate complexity (3 parameters, no annotations, but with output schema), the description covers the basic purpose and parameters adequately. However, it lacks important context about when to use versus the sibling tool, behavioral constraints, and error handling. The existence of an output schema reduces the need to explain return values, but other gaps remain.

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 provides meaningful semantic context for all three parameters beyond the schema's 0% coverage. It explains that 'city' is a city name with an example, 'country' is an optional filter with format examples, and 'days' specifies the forecast range with constraints (1-7). This compensates well for the schema's lack of 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 states the tool's purpose: 'Get a simple daily weather forecast for the next N days for a city.' It specifies the verb ('Get'), resource ('daily weather forecast'), and scope ('for a city'), though it doesn't explicitly differentiate from its sibling tool 'get_current_weather' beyond implying this is for forecasts rather than current conditions.

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 its sibling 'get_current_weather' or any alternatives. It mentions the tool's basic function but lacks explicit when/when-not instructions or prerequisite context, leaving usage decisions to inference.

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