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

With no annotations, the description carries the full burden and does most of it: discloses credit cost, that output is faithful with no new content, and that the call is asynchronous (returns a job, needs polling). It doesn't mention validation failure modes (bad imageId, unsupported source) or whether credits are refunded on failure, which keeps it short of a 5.

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 compact clauses, zero filler: capability and constraint first, then cost, then parameter provenance, then the async follow-up. Every sentence earns its place and the critical information is 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?

For an async mutation tool with no output schema, the description supplies what an agent needs: cost warning, source of the required id, and the polling path. A brief note on the job object's shape or what happens on invalid input would close the last gap.

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 scale, imageId, and requestId idempotency are already documented in structured fields. The description adds provenance for imageId, which is genuinely useful, but nothing extra on scale defaults or requestId retry semantics beyond what the schema states. Baseline 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 (upscale) and resource (one of your own generated images), plus scope qualifiers: 2x or 4x, faithful, no new content. That distinguishes it from ryla_generate_image and ryla_generate_base_image, which create content rather than enlarge existing output.

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?

Explicitly tells the agent where imageId comes from (ryla_generation_status output.imageIds or ryla_account_gallery_list) and the follow-up workflow (poll with ryla_generation_status). No explicit when-not-to-use case, e.g. that non-owned or externally sourced images can't be upscaled, but the 'your own generated images' phrasing implies it.

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