Fetch a contact’s photo

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

Annotations already declare readOnlyHint, idempotentHint, and destructiveHint false. The description adds meaningful behavioral context by explaining that linked photos are never fetched because the address was chosen by the card writer, and that only embedded photos are returned. It does not cover edge cases like missing photos, but the annotations lower the burden.

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?

Two sentences with no filler. The main return behavior is front-loaded, and the caveat about linked photos follows naturally. Every sentence earns its place.

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 simple one-parameter read-only tool with an output schema, the description covers selection, invocation context, and the key boundary case. It could more explicitly state what happens when no embedded photo exists, but the annotations and schema fill most of the remaining context.

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 sole id parameter has 100% schema coverage and a clear description listing its source tools. The tool description does not add extra parameter-level meaning beyond that, so the schema carries the weight and the baseline of 3 is appropriate.

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 states a specific verb and resource: it returns the photo stored on a card as an image. It also distinguishes itself from get_contact by clarifying that linked photos are reported by get_contact and never fetched, so an agent can tell the two tools apart.

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 names get_contact as the alternative and gives a clear condition: use this tool for photos embedded in the card itself, and get_contact for photos stored as links. This explicitly tells the agent when to use the tool and when not to.

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