render_qr_terminal

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

With no annotations provided, the description carries the full burden of disclosing behavior. It explains that the tool returns an ascii_qr field that can be pasted directly, and it details the domain_mismatch conditional behavior. This adequately covers the tool's non-destructive, output-generating nature and error handling.

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 a single paragraph that front-loads the main purpose, then provides usage guidance and error handling. It is concise with no redundant information, earning its place with every sentence.

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?

Given the tool's simplicity (one parameter, no nested objects, output schema exists), the description covers the main use case, output format, and the important domain_mismatch edge case. It is complete enough for an AI agent to understand when and how to use the tool.

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 description does not explicitly describe the login_id parameter or its source, but the context strongly implies it comes from begin_login. Schema coverage is 0%, so the description should compensate; it partially does by referencing 'the login QR code from begin_login', but an explicit statement linking login_id to begin_login would improve clarity.

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 specifies that the tool renders a login QR code from begin_login into a plain text terminal QR code (Unicode half-block characters) for CLI/TUI scenarios. It distinguishes itself from siblings like begin_login, which generates the QR code data, making the purpose unambiguous.

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 tells when to use the tool (after begin_login returns a QR code) and provides explicit guidance on handling domain_mismatch (do not show, recall begin_login). It also states what the caller does not need to do (download images, call system tools). However, it does not explicitly exclude sibling tools or provide criteria for choosing between them, though the context is clear.

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