setup_credentials

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

With no annotations, the description carries the burden. It details encryption at rest and no plain text storage. However, it omits key behaviors: whether existing credentials are overwritten, what happens on login failure, and any prerequisites (e.g., vault availability).

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 sentences, each serving a distinct purpose: action, usage condition, security detail. No fluff, well-structured.

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 credential storage tool, it explains encryption and immediate login. However, it lacks details on return values, error handling, and overwrite behavior. Sibling tools like check_credentials and clear_credentials provide some missing context, but the description could be more complete.

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?

Input schema provides 100% coverage with descriptions for email and password. The description adds no additional meaning beyond the schema's declarations, so baseline 3 is appropriate.

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 states a specific verb+resource: store Garmin Connect credentials and log in. It clearly distinguishes from siblings like check_credentials (which only checks) and clear_credentials (which removes).

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?

Explicitly says 'Use this when the server reports that credentials are missing or invalid.' This provides clear when-to-use context, but does not mention alternatives or when not to use, such as if credentials are already valid.

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