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

Goes beyond the readOnly/idempotent/non-destructive annotations by declaring 'Makes no file' and detailing validation behaviour: unsupported formats (HEIC, WebP, GIF, TIFF) and damaged or oversized files are flagged rather than raising an error. What is missing is any hint about failure handling beyond per-file flags or any limits on response size for 60 images.

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 trigger condition, then the returned fields, then capabilities and exclusions — good information ordering. The middle sentence is a long comma-and-'and' list of reported fields and rejected formats, which is dense but each clause carries distinct information, so there is little true waste.

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 read-only inspection tool with a full input schema and an output schema, this covers what to do, what comes back conceptually, what counts as unusable input, and what it does not do. An agent can decide to call it and interpret the result without further guidance.

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 description coverage is 100%, so fit, margin_mm, page_size and orientation are already fully documented, including defaults and the 'ignored for fit' rule. The description's only added parameter meaning is that it accepts the same page options as images_to_pdf, which helps consistency but does not explain any individual argument.

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?

Names a specific verb and resource (inspect attached JPG/PNG photos and scans) and enumerates exactly what is reported per file: type, pixel size, EXIF orientation and needed rotation, DPI, colour mode, and resulting page size. It also states the negative space it covers (unsupported formats, damaged, too large), which cleanly separates it from images_to_pdf.

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?

Explicit trigger ('when the user wants to check photos or scans before making a PDF') plus explicit exclusions ('Do not use for reading text in an image (no OCR) or for editing images'). It also points to the sibling workflow by noting it takes the same page options as images_to_pdf, so the agent knows this is the pre-flight step before that conversion.

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