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

readOnlyHint=true already establishes this as a safe read, so the bar is lower. The description adds useful framing (what a project contains and that its projectId feeds other tools), but says nothing about pagination behavior or result ordering beyond what the schema's page_token already implies.

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?

Three tight sentences, front-loaded with the core action, then the domain definition, then the practical follow-up. The trailing 'Depot: ProjectService/ListProjects' internal reference earns its place only marginally but costs little.

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 read-only, zero-required-parameter list tool with full schema coverage and no output schema, the description is nearly sufficient: purpose, entity definition, and how to use the result are all present. Only pagination-flow behavior is left implicit.

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 100%, so page_size, region_id, and page_token are fully documented in the schema. The description adds no syntactic or semantic detail about any of them, so the baseline 3 applies.

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?

States a specific verb and resource ('List the organization's Depot projects') and then defines what a project is ('an isolated container-build cache with region, hardware, cache policy'). This distinguishes it from the singular sibling depot_get_project and from depot_list_builds / depot_list_registry_images without any schema lookup.

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?

Provides clear downstream context: 'Use the returned projectId with the build and registry tools.' That tells the agent why and when to call it, but it never names alternatives (e.g., depot_get_project for a single project) or states any exclusion condition, so it stops short of a 5.

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