clinicaltrialsgov-mcp-server

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

Annotations declare readOnlyHint/idempotentHint/openWorldHint. The description adds valuable behavioral context: 'Returns the full study record' clarifies the data scope beyond what annotations provide, and the resource equivalence explains implementation intent. No contradictions with 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?

Three sentences, zero waste. Front-loaded with core action ('Fetch a single clinical study'), followed by return value, then resource equivalence note. Every sentence earns its place.

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?

Tool has low complexity (1 param), 100% schema coverage, and output schema exists. Description appropriately does not duplicate return schema details, but confirms 'full study record' scope. Resource equivalence note completes the usage context.

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 has 100% description coverage with pattern and example for nctId. The description references 'NCT ID' but does not add semantic meaning, syntax help, or constraints beyond what the schema already documents. Baseline 3 appropriate when schema carries full load.

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 uses specific verb 'Fetch' with resource 'clinical study' and scope 'single...by NCT ID'. It clearly distinguishes from siblings like 'search_studies' (multiple) and 'get_study_results'/'get_field_values' (partial data) by specifying 'single' and 'full study record'.

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?

Provides explicit context for when to use this tool: 'Equivalent to the clinicaltrials://{nctId} resource for clients that do not support MCP resources'. However, lacks explicit contrast with 'search_studies' for when the user doesn't know the exact NCT ID.

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