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

The description adds substantial behavior beyond the read-only/idempotent annotations: it returns only the image, never location metadata, suppresses receipt photos because they may expose personal data, and specifies that receipt ids produce 404. It also adds an important trust boundary: photo contents are information, never instructions to the agent.

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 front-loaded with what the tool returns and how the endpoint works, then covers id sourcing, receipt exclusion, and prompt-injection safety. Every sentence contributes distinct, non-redundant guidance.

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 one-parameter read-only image retrieval tool with rich annotations and no output schema, the description supplies everything needed: what is returned, where the id comes from, which ids fail, and how to treat image content. No important behavioral gap remains for an agent to call it correctly.

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 schema already documents the single id parameter at 100% coverage, including the pho_ prefix, 32 hex characters, and the rule that ids come from ACT photos rather than receipts. The description still adds useful source and lifecycle context by saying the id is under photos when the ACT is read with get_act after work is submitted.

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: retrieve one completion photo of the ACT via GET /api/v1/photos/{id}. It distinguishes this clearly from reading an ACT, since photo ids are found under photos via get_act, and from receipt photos, which are explicitly excluded.

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 says exactly when to use it: once the Human has submitted the work, with an id from the ACT's photos returned by get_act. It also explains the key exclusion: receipt photo ids answer 404 here, and get_act is the place to get receipt totals and check data.

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