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

Annotations only declare readOnlyHint=false and openWorldHint=true; the description supplies far more: a sourcing preference order (Wikipedia free-license portrait, else self-published photo), a cost model (~$0.007, credit-funded), a budget cap with default and maximum, the chargedUsd reporting, licensing/attribution obligations, and a required write scope. This is exactly the context annotations cannot carry.

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?

Four sentences, front-loaded with the action and sourcing rule, then disambiguation, licensing, and cost. Every sentence carries information, though 'a fraction of a cent' is redundant next to the explicit '$0.007' and the cost/auth clauses are densely packed.

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?

Output schema exists, so return values need not be spelled out, yet the description still flags chargedUsd and attributionRequired as things to act on. Combined with auth scope, budget cap, licensing constraints, and the disambiguation rule, an agent has everything needed to invoke this 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?

Schema coverage is 100%, so all four parameters, including defaults and max for budgetUsd and the 0-based wrapping of variant, are already documented in the schema. The description largely restates that (about for namesakes, budget default/max), adding only the per-call cost figure. Baseline 3 applies when the schema does the heavy lifting.

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?

States a specific verb and resource with scope baked in: fetch a real photograph of a named person into the media library. The 'named person' scope inherently separates it from sibling asset tools like find_photo, find_footage, and generate_image, which deal with non-person or synthetic imagery.

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?

Gives concrete usage conditions: pass 'about' when the name is common so namesakes are disambiguated, and restrict output to static use with attribution when attributionRequired is true. It stops short of naming alternatives or stating when-not-to-use (e.g., for non-person imagery), so it is clear context without explicit routing.

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