generate_image

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

Annotations already declare readOnly=false, idempotent=false, openWorld=true and destructive=false, so the safety profile is covered. The description adds genuinely new context beyond that: the request is paid, retries are not automatic after timeout/failure, and 'existing files are protected'. It does not cover auth/permission requirements, but the marginal behavioral value is solid.

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 short sentences, front-loaded with the action and cost implication, then output behavior, then the retry rule and file-protection guarantee. Nothing is padded or redundant.

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 no output schema, the description helpfully characterizes the return ('paths/metadata or a job ID to poll with get_job') and covers cost, non-resubmission and file safety. For a 7-parameter paid mutation tool this is close to complete; the only gap is explicit prerequisite/alternative routing relative to edit_image and list_models.

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 71%, so the schema already documents model, prompt, output_path, n, size and quality in meaningful detail (format constraints, charge implications, provider defaults). The description adds no parameter-level syntax or defaults of its own. Baseline 3 is appropriate when the schema is doing the heavy lifting.

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: 'Submit one paid image-generation request and save bytes locally', which an agent can distinguish from a sibling like edit_image by the generation-vs-edit framing. It also routes polling to get_job. It stops short of explicitly naming the alternatives it is not (edit_image, list_models), so it is clear but not fully sibling-differentiating.

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?

'Returns paths/metadata or a job ID to poll with get_job' gives real routing guidance, and 'Never automatically resubmit after timeout/failure' bounds retry behavior. However, there is no explicit statement of when to choose this over edit_image, nor any precondition (e.g., model must first come from list_models). Usage is implied rather than stated.

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