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

The description discloses behavior beyond the readOnlyHint annotation: it specifies that the tool returns all projects for the calling subscriber, lists the exact fields returned, and explains the tier restriction (anonymous callers get a 'TIER_INSUFFICIENT' envelope). There is no contradiction with the annotation.

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 concise (three sentences) and front-loaded: the first sentence states the purpose and outputs, the second provides usage context, and the third states restrictions. Every sentence adds necessary information without redundancy.

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 parameters and an output schema (implied by context signals), the description is complete: it explains what the tool does, when to use it, what data it returns, and who can use it. No additional information is needed.

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?

With zero parameters and 100% schema coverage, the baseline is 4. The description does not need to add parameter information since there are none. It adds value by describing the return fields, which complements the missing output schema.

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 ('List every project saved by the calling subscriber') and the resource ('projects'). It distinguishes itself from sibling tools like 'get_project' and 'recompute_project' by targeting a different use case (listing vs. fetching or computing). The inclusion of specific fields enhances clarity.

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 explicitly tells when to use the tool: 'Use this to re-find a saved project from a new conversation when its project_id is no longer in context.' It also provides guidance on subsequent steps ('pass the project_id to get_project or recompute_project') and warns about tier restrictions ('Paid tier only'), effectively excluding unauthorized users.

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