imagepeek: read QR codes and barcodes from an image

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

Goes well beyond the readOnly/idempotent/openWorld annotations: it discloses latency (0.5-2 s), price (USD 0.002), a free-tier rate limit (3 calls per IP per UTC day), a failure mode ('Damaged or tiny codes may be missed'), a security posture ('Images are never logged or stored') and prompt-injection guidance for the decoded payload. That is unusually rich behavioral context for a read tool.

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?

Front-loaded with the core action and the sibling routing before moving to output detail, price and caveats. It loses a point for a duplicated untrusted-data warning appearing twice in slightly different wording, which is minor waste in an otherwise dense, earned block of text.

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 zero-required-parameter read tool with an output schema, everything an agent needs is present: input alternatives, return shape, exclusions, latency, cost and rate limit. Nothing material is missing even though the output schema already covers return values.

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?

Schema coverage is already 100%, so the baseline is 3, but the description adds real meaning on top: it explains the emv field emitted when parse_emv triggers, the 000201 EMVCo prefix and supported schemes, and the CRC check performed. It does not restate the url/image_base64 alternatives, which the schema handles.

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?

States a specific verb+resource ('Read every QR code and barcode in an image') and explicitly distinguishes itself from siblings, routing QR generation to make_qr_code and plain text extraction to ocr_image. An agent can pick this tool versus its neighbors without opening any schema.

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?

Names two concrete alternatives with the condition that selects each ('To make a QR code use make_qr_code; for other text use ocr_image'), and adds negative guidance by listing unsupported symbologies (Data Matrix, PDF417, Aztec). Nothing about when to use this is left to inference.

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