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

Annotations provide no meaningful safety signals since readOnlyHint and destructiveHint are both false, so the description carries the behavioral burden. The description adds useful context: it sharpens and upsizes an existing photo and does not generate new imagery. However, it does not disclose return behavior, whether a new file is produced, or side effects beyond the operation itself.

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 two sentences with no filler and front-loads the core operation immediately. The second sentence usefully clarifies it transforms an existing image rather than generating a new one. It earns its length and is easy to scan.

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?

The schema covers parameters thoroughly, including timeouts and format constraints, but there is no output schema and the description does not state what the tool returns or how the result is delivered. The tool sits among many related photo tools, and the description does not position it relative to them. For a moderately simple transformation tool, this is adequate but not fully complete.

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%, and every parameter already has useful per-parameter explanations, including defaults, timing expectations, and default behaviors like invalid scale silently falling back to 2. The description itself rephrases scale and face_enhance but adds little beyond the schema. The phrase 'super-resolution detail recovery' does add some model-selection context, but it is not enough to raise the score above the baseline.

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 clearly says the tool enlarges an existing image 2x or 4x with super-resolution detail recovery and an optional face-enhancement pass. It is more specific than the tool name and adds useful nuance ('does not generate new imagery'). However, it does not explicitly differentiate from the nearby sibling photo_resize, which may also handle enlargement.

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?

The description implies use for upscaling existing photos but gives no explicit 'when to use this vs alternatives' guidance. It never mentions photo_resize, photo_editor, or related image tools, nor does it state a condition such as 'use this only when super-resolution detail is needed'. The 'does not generate new imagery' exclusion is helpful but is more about disqualification than active routing.

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