GCP MCP

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

With no annotations provided, the description carries full burden. It discloses the authentication method ('browser-based OAuth flow') and mentions the optional project_id parameter, but doesn't describe important behavioral aspects like whether this initiates a new browser window, what happens if already authenticated, error conditions, or timeout behavior. It provides basic context but lacks operational details.

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 perfectly structured with a clear purpose statement followed by Args and Returns sections. Every sentence earns its place, providing essential information without redundancy. The formatting with clear sections makes it easy to parse.

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 an authentication tool with no annotations and no output schema, the description provides adequate basics but lacks depth. It explains what the tool does and the parameter, but doesn't cover important authentication-specific context like required browser interaction, session management, error handling, or what 'successful' authentication actually means in practical terms.

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 0% schema description coverage and only 1 parameter, the description adds significant value by explaining the project_id parameter's purpose ('Optional project ID to set as default after login'). This goes beyond the schema's minimal documentation, though it doesn't specify format constraints or provide examples.

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 specific action ('Authenticate with Google Cloud Platform') and method ('using browser-based OAuth flow'), distinguishing it from sibling tools like auth_list or auth_revoke. It provides a complete verb+resource+method combination that leaves no ambiguity about what this tool does.

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 implies this is the primary authentication entry point ('Authenticate with Google Cloud Platform'), suggesting it should be used to establish initial credentials. However, it doesn't explicitly state when NOT to use it (e.g., after already authenticated) or mention alternatives like auth_list for checking current authentication status.

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