tool_upscale_image

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

With no annotations, the description carries the full behavioral burden. It helpfully discloses that upscaling happens by re-rendering with a generative model (implying output is synthesized, not a faithful resample), but says nothing about file-side effects (writing to output_path/output_filename), cost, overwrite behavior, or permission needs.

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?

One sentence, front-loaded with the verb and resource, with no filler. Every clause adds information (target resolutions, mechanism).

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?

Covers what the tool does and its output targets, but with no output schema and no annotations the description should say what comes back (saved file path vs. base64) and note the disk-writing side effect. Adequate minimum for calling the tool, incomplete for predicting its effects.

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 description contributes zero parameter detail; the reported top-level coverage is 0% only because everything is nested under a single 'params' $ref. The nested schema properties are in fact richly documented (model_name limits, model_tier overrides, output_path precedence, target_resolution aspects), so the schema does the heavy lifting and a baseline 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?

States a specific verb (upscale), resource (image), the target outputs (2K/4K), and the mechanism (re-render with a Gemini image model), which distinguishes it from generate_image/edit_image/transform_image without naming them. It stops short of explicitly contrasting with those siblings, so it is clear but not self-routing.

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?

No when-to-use guidance and no acknowledgement of the nearby alternatives (transform_image, edit_image, generate_image). An agent has to infer that this is for low-resolution source images that need resolution increase, rather than being told.

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