JSONPlaceholder MCP Server

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

No annotations are provided, so the description carries full burden. It states the tool retrieves photos but doesn't disclose behavioral traits such as whether it's read-only, requires authentication, has rate limits, returns paginated results, or what happens with invalid inputs. The description is minimal and misses key operational details.

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 purpose ('Retrieve photos') and adds optional details. There is no wasted text, making it appropriately sized and well-structured for quick comprehension.

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 no annotations, 0% schema coverage, and no output schema, the description is incomplete. It covers the basic purpose but lacks details on behavior, parameter usage, return values, and error handling. For a retrieval tool with two parameters, this leaves significant gaps in understanding how to use it effectively.

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 0%, so the description must compensate. It mentions 'filtered by album ID or get a specific photo', which loosely maps to the two parameters (album_id, photo_id), but doesn't explain their semantics, interactions, defaults, or constraints. The description adds some meaning but is insufficient for full parameter understanding.

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: 'Retrieve photos' with optional filtering by album ID or specific photo. It uses a specific verb ('Retrieve') and resource ('photos'), though it doesn't explicitly distinguish from sibling tools like 'get_albums' or 'get_users' which retrieve different resources.

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 'optionally filtered by album ID or get a specific photo', suggesting when to use parameters, but provides no explicit guidance on when to choose this tool over alternatives like 'get_albums' or general search tools. It lacks context on prerequisites or exclusions.

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