start_qr_login

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

The annotations already declare readOnlyHint=true and openWorldHint=true, and the description adds important behavioral context: it does not write local credentials, whereas complete_qr_login does. It does not mention auth requirements or rate limits, but the core side-effect distinction is clearly disclosed.

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 very short and front-loaded with the return value, then adds the credential-writing distinction. The English parenthetical '(QR code login)' is somewhat redundant, but the overall structure is efficient and wastes little space.

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 simple login-start tool with annotations covering safety and no output schema, the description adequately states what is returned and how it relates to complete_qr_login. It could say more about the login workflow sequence, but it is complete enough for correct invocation.

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?

There is one required parameter, and schema description coverage is 100%. The schema already explains the description parameter format, and the tool description adds no further meaning about that parameter, so the baseline of 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 and resource: returns an inline QR code image and the corresponding link URL. It also distinguishes itself from the sibling complete_qr_login by explicitly saying credentials are not written locally and that complete_qr_login handles writing them.

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 gives clear workflow context by naming complete_qr_login as the credential-writing step, which implies this tool starts the QR login flow. It does not explicitly state when not to use this tool or list alternative login-status tools, but the context is sufficient for an agent to route correctly.

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