Read a downloaded image

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

Annotations already declare readOnlyHint=true and openWorldHint=false, so safety is covered. The description adds meaningful behavior beyond that: no OCR, no AI provider call, the returned artifact is a raw JPEG/PNG for the caller's model to interpret. It stops short of error/edge behavior (missing file, non-image path), but adds real value over the annotations.

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 compact sentences with the key qualifier ('Read-only.') front-loaded, followed by return type and parameter mechanics. Every sentence contributes, though the 'for the user to have you read it with your own model' clause is slightly verbose relative to the information it carries.

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 2-parameter, read-only tool with no output schema, the description covers return type, permitted sources, and path/runId semantics — everything needed to invoke it correctly. It omits failure modes (file not found, unsupported format) and any size/count limits, which is a minor gap given the tool's simplicity.

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 only 50% (runId has no schema description), yet the description compensates: it explains that a run file is passed with its runId and a path relative to the run dir, versus an absolute path for a browser_act download. That ambiguity resolution (relative + runId vs absolute) is exactly what the schema leaves unclear, though the runId's own format/constraints remain unstated.

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 ('Returns a JPEG or PNG ... as an image') plus the exact sources it reads from (run evidence, run file, browser_act download). It also sharply distinguishes itself from anything that might be assumed to do OCR or call a model ('Ritoko does no OCR and calls no AI provider'), so an agent understands what kind of read this is without opening another schema.

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 clear context for when to reach for it: when the user needs the agent's own model to see a downloaded/captured image, and it names the three concrete origins (run evidence, run file, browser_act download). It does not name an explicit alternative tool or a 'when not to use' case, so it stops short of full routing guidance.

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