session_qr_image

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 only states that it returns a QR code image, but does not mention any side effects, prerequisites (e.g., session must be active), output format (e.g., PNG, base64), or whether it is a read-only operation. This is sparse behavioral information for an agent.

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 short but contains redundancy: 'Get session QR code as image' is immediately followed by 'QR code as image of the session with the given session ID,' which restates the same idea. It could be condensed to one clear sentence without losing information. This is not an egregious waste, but it is not optimally concise.

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?

The tool is simple (one parameter, no output schema), and the description gives a minimal but functional understanding of its purpose. However, it omits details that would help an agent, such as the image format, whether the session must be active, or any error conditions like 'session not found.' Given the lack of annotations and output schema, the description leaves some important gaps for practical use.

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 input schema already provides full documentation for the single parameter 'sessionId' (type, example, format rules, and description), giving 100% coverage. The tool description adds 'with the given session ID' but this is redundant with the schema. Since schema coverage is high, the baseline of 3 is appropriate; the description does not meaningfully enhance parameter understanding.

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 tool's function: 'Get session QR code as image.' It uses a specific verb ('get') and resource ('session QR code'), and the phrase 'as image' distinguishes it from siblings like session_qr, which might return the QR code in another format. The parameter 'session ID' is also referenced, 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 provides no guidance on when to use this tool versus alternatives like session_qr or session_requestPairingCode. It does not mention that this is the image-returning variant or when an image is preferred. No exclusions or prerequisites are stated, leaving the agent to infer usage from the name alone.

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