JSONPlaceholder 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 retrieval and filtering but fails to describe key behaviors such as whether this is a read-only operation, what permissions are needed, how results are returned (e.g., pagination, format), or any rate limits. This leaves significant gaps for an agent to understand the tool's 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, efficient sentence that front-loads the core action ('retrieve comments') and adds necessary detail about optional filtering. There is no wasted language, and it is appropriately sized for the tool's complexity, making it highly concise and well-structured.

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 has no annotations, no output schema, and 0% schema description coverage, the description is incomplete. It covers the basic purpose and parameter intent but lacks information on behavioral traits, return values, error handling, or how it differs from siblings. For a retrieval tool with two parameters, this leaves too many contextual gaps.

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 schema description coverage is 0%, so the description must compensate for undocumented parameters. It adds some meaning by explaining that parameters allow filtering by post ID or getting a specific comment, which clarifies the purpose of 'post_id' and 'comment_id'. However, it doesn't provide details on parameter interactions, defaults, or constraints, leaving semantics partially unclear.

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 verb 'retrieve' and resource 'comments', making the purpose understandable. It specifies optional filtering by post ID or getting a specific comment, which adds specificity. However, it doesn't explicitly differentiate from sibling tools like 'get_posts' or 'search_posts', keeping it from a perfect score.

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 implies usage through the mention of optional filtering parameters (post_id or comment_id), suggesting when to use these options. However, it lacks explicit guidance on when to choose this tool over alternatives like 'get_posts' or 'search_posts', and no exclusions or prerequisites are stated, making the guidance incomplete.

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