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

Annotations already declare readOnlyHint, openWorldHint, idempotentHint, and destructiveHint, covering the safety profile. The description adds meaningful behavioral context: the matching behavior on companyName and the caution not to silently mix projects. It also reveals that results depend on the API key's permissions. This goes beyond annotations, though it does not describe return format or pagination, which are reasonable gaps for a read-only list tool.

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 with no filler. The first sentence front-loads the primary purpose, and the second provides usage guidance and a caution. Every word adds value; the structure is optimal for agent 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?

For a no-argument, no-output-schema tool, the description provides all necessary context: what it returns, when to use it, and a behavioral constraint. It is complete enough for an agent to know when and how to call it without ambiguity. The lack of pagination or return-format details is not a gap given the tool's simplicity.

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, so the description does not need to explain any. The baseline for zero parameters is 4, and the description adds no parameter-specific details but does not need to. It implicitly explains how the tool behaves (matching on companyName), which is contextually relevant.

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 action: 'Resolve which Space Monkey projects this API key can read.' It specifies the resource (projects) and the scope (readable by API key). It also distinguishes itself from sibling list tools by focusing on projects and the companyName matching behavior, which is a unique identifier. No confusion with other tools.

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 when-to-use guidance: 'Call this first when the user names a company rather than a project ID.' It contrasts with project IDs, implying that for project IDs a different tool would be used. However, it does not name the alternative tool, leaving some inference to the agent. The 'never silently mix projects' rule further clarifies safe usage.

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