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

Beyond annotations, the description discloses immediate effect, that nothing is deployed, how credentials are obtained via GetProject include_secret_values, the return value, and concrete error mappings including DatabaseLinkRefusal causes. This gives the agent substantial operational context for a destructive mutation.

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 front-loaded with the core purpose and is dense but generally efficient. The terse error-code notation and packed clauses reduce readability slightly, but there is little wasted content.

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 3-parameter mutation tool with no output schema, the description covers purpose, effects, credentials, return value, and key failure modes. An agent has enough information to invoke it correctly and anticipate common errors.

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 schema already describes link and unlink, but database_project_id has no schema description. The description compensates by stating it must be a database project and explaining the resulting host/port behavior, while also clarifying the mutual-exclusion constraint between link and unlink.

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 a specific action: linking projects to a database project so they can reach it. It also explains the resulting host/port behavior and sign-in mechanism, making the tool's purpose distinct from siblings such as CreateDatabase or CreateProject.

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?

It explains when linking takes effect and notes that both link and unlink can be used, with a specific INVALID_ARGUMENT rule for overlapping IDs. It does not explicitly compare this tool to sibling alternatives, so it falls short of full when-to-use/when-not guidance.

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