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

With no annotations, the description carries the full burden and does meaningful work: it discloses that only self-declared claims are read and that those claims are 'easy to strip or fake,' setting reliability expectations. It omits operational traits like auth requirements, rate limits, or what a null/empty result looks like.

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?

Three short sentences, front-loaded with the core action and payload, followed by input selection and the interpretative caveat. Every sentence contributes; there is no filler.

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 3-parameter, zero-required, no-output-schema tool, the description effectively describes the return payload (the enumerated signal types) and the input constraint, so an agent can call it correctly. It could still note the response shape when no metadata is present.

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, and the description adds the non-obvious mutual-exclusion rule ('image_url ... or image_base64, not both') that the schema itself does not state. That is genuine added value beyond the structured fields.

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 names a specific verb (Read/check), a specific resource (an image file's own metadata), and enumerates exactly what is extracted: C2PA Content Credentials, IPTC source type, creator tool, embedded prompts. The image-file scope inherently separates it from the text/URL siblings (scan_text, scan_url, find_hidden_instructions).

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?

It gives clear operating guidance — 'Pass image_url (https) or image_base64, not both' — and frames how to act on the result ('Signal, not a verdict... Never accuse anyone on this alone'). It does not, however, explicitly route the agent to or away from a sibling tool, so it stops short of a 5.

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