US Government Open Data MCP

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

Annotations provide readOnlyHint=true, indicating a safe read operation. The description adds valuable context beyond this: it specifies the data range ('1900–2018'), lists allowed enum values for race and sex, and notes the limit parameter default ('default 200'). This enriches the agent's understanding of the tool's behavior without contradicting annotations.

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 highly concise and front-loaded: the first sentence states the core purpose, followed by essential details (enum values, data range, alternative tool). Every sentence adds necessary information without fluff, making it efficient for an agent to parse and understand.

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 (4 parameters, no output schema), the description is nearly complete. It covers purpose, usage guidelines, key constraints, and references a sibling tool. The main gap is lack of output details (e.g., format of returned life expectancy values), but annotations indicate it's read-only, and parameters are well-documented, so it's mostly sufficient for 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?

Schema description coverage is 100%, with each parameter well-documented in the schema (e.g., year range, enum values, limit default). The description mentions the data range and enum values, but this largely repeats schema information. It adds marginal value by emphasizing the temporal constraint and listing enums explicitly, aligning with the baseline score for high schema coverage.

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 specific action ('Get U.S. life expectancy at birth'), resource ('by race and sex'), and temporal scope ('1900–2018'). It explicitly lists the valid race and sex values, making the purpose distinct and unambiguous. This directly helps an agent understand what data the tool retrieves.

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 explicit guidance on when to use an alternative tool: 'For more recent mortality trends, use cdc_mortality_rates.' This clearly distinguishes this tool (historical data up to 2018) from its sibling for newer data, helping the agent choose correctly based on recency needs.

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