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

No annotations are provided, so the description must convey behavioral context. It does so by specifying 'for the authenticated user' (auth context) and 'Lists all' (scope). It also reveals that the output includes a platform ID. However, it does not explicitly state that the operation is read-only or describe the response structure, though the output schema likely covers that.

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 two sentences, front-loaded with the core action. The second sentence provides a practical use case without redundancy. Every word earns its place, 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's simplicity, the description covers the essential aspects: what it does, for whom, and a key use case. The presence of an output schema means return value details are not strictly needed. It lacks explicit mention of edge cases (e.g., empty list) but is complete enough for a basic list tool.

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 tool has zero parameters and the schema is vacuous, so the baseline is 4. The description adds no parameter-specific information because none is needed. It does add value by explaining the purpose of the output (platform ID), which indirectly informs why there are no parameters.

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 function: 'Lists all external platforms (projects) for the authenticated user.' The verb 'Lists' and the resource 'external platforms' are specific, and the parenthetical '(projects)' clarifies terminology. It also distinguishes itself from other list tools by highlighting the platform ID discovery use case, which is unique among siblings.

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 the tool: 'Use this to discover your platform ID.' It also implies when it is not needed by noting that 'other tools auto-resolve if omitted.' While it does not name specific alternative tools, this is clear enough for selection in most contexts.

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