Screenshot Generate Sample

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

Annotations already disclose readOnly=false, openWorld=true, idempotent=false, destructive=false, so the safety profile is covered. The description adds genuinely non-derivable context: the operation is '(paid)' (a real cost implication) and it writes to a specific on-disk path, which explains why it is a write with destructiveHint=false. Return shape is restated but that is minor.

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 tight lines: what/where/cost first, then usage, then return. No filler, and the most decision-relevant facts (paid, output path, automatic invocation by screenshot_build_all) are front-loaded.

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?

With only two fully documented parameters, an existing output schema, and annotations covering the safety profile, the description supplies everything an agent needs: purpose, cost, artifact location, and the orchestrator relationship. Nothing material is missing.

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 both prompt and app_dir are already documented with examples in the schema. The description adds no syntax, format, or constraint detail beyond the schema, so the baseline of 3 applies.

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 ('Generate a sample image'), names the external service (fal.ai), and gives the exact output artifact path (Resources/sample_headshot.jpg) plus the UI purpose (fill Result/Gallery screens). This is clearly distinguishable from sibling screenshot_capture, screenshot_brand, and screenshot_apply_layout.

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?

'Use when: screenshots need real-looking app output' gives a clear triggering condition, and 'screenshot_build_all calls it for you' tells the agent it is normally invoked transitively rather than directly. There is no explicit when-not-to-use or a named alternative for the manual path, 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.