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

Annotations already declare readOnly/idempotent/non-destructive, yet the description adds genuinely new behavior: the call never blocks, polling is prohibited, and the `status` state machine is spelled out including the terminal `failed` case where `error.message` carries the reason. It even prescribes how to present the result rather than dumping JSON.

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?

Front-loaded with the core identity, then WHEN, then anti-patterns, then output handling. Every sentence carries distinct information; no filler or restatement of the title.

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 still explains the returned status values, where the finished file lives (`url`), and where failure reasons appear (`error.message`). For a one-param read tool this is fully sufficient to call and interpret correctly.

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 100% and the single `id` param already documents its provenance ('The job id returned by `generate_image`'). The description adds no further syntax, format, or validation detail beyond what the structured schema supplies, so the 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 and resource ('One image job's current state: a SINGLE, IMMEDIATE read that waits for nothing') and immediately contrasts with `wait_for_generation`, `generate_image`, and `show_generation`. An agent can pick this over any sibling without opening a 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?

Explicit WHEN clause ('only for one job's raw fields now'), explicit negative guidance ('Do not poll it'), and named alternatives for both the waiting case and the display case. When-to-use and when-not-to-use are both covered.

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