Inspect an image

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

With no annotations provided, the description carries the full burden. It does disclose the non-destructive nature ('without modifying it'), which is a key behavioral trait. However, it omits other behavioral details such as network fetch requirements (the URL parameter is disabled unless PICTOR_ALLOW_NET_FETCH=true) and potential error cases, so it is only partially transparent.

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, efficient sentence that front-loads the core purpose and lists the metadata types concisely. There is no wasted text, and it is appropriately sized for the tool's simplicity.

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 has an output schema, so the description does not need to explain return values. The description covers the main purpose and the non-destructive aspect. However, it could mention the multiple input methods (URL, path, base64) but those are documented in the schema, so the description is sufficiently complete for an agent to understand the tool's function.

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 the baseline is 3. The description does not add any meaning beyond what the schema already provides for parameters; it only lists output categories without linking them to inputs. Thus it meets the baseline without adding value.

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 a specific action (read metadata) and a specific resource (an image), and explicitly lists the metadata types (dimensions, format, colour mode, etc.). It distinguishes itself from sibling tools, which are largely modification tools (resize, transform, convert), by emphasizing non-modification.

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 clear context: it is a read-only inspection tool, implicitly excluding modification operations. However, it does not explicitly name alternative tools or conditions for when to use this tool over siblings like image_capabilities, so it falls short of a 5 but is above a 3.

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