Job status

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

Annotations already declare readOnly/idempotent/non-destructive, so the safety profile is covered; the description adds genuinely non-schema behavior such as signed result URLs expiring after 15 minutes and the job being free of credit cost. It does not explain what 'final' means for failed jobs or what happens when an id is unknown in both lookups, which keeps it below 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?

Front-loaded with the return payload, then the when-to-use rule, then cost — a sensible ordering with no filler. The 'Credits: free, no credits' phrasing is mildly redundant but earns its place by answering a cost question up front.

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?

Given an output schema exists, the description goes beyond the minimum by supplying the polling loop, the alternative tool at completion, and the URL expiry constraint an agent must act on immediately. Nothing needed to call this correctly is missing.

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 schema already documents the id pattern, the kind fallback lookup order, and the waitSeconds/timeout tradeoff. The description only restates the waitSeconds polling idea ('progress notifications are sent when your client asks for them'), adding little meaning beyond the schema.

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 ('returns the status of a generation or a screenshot set by id') and enumerates the returned fields (status, final, image counts, credits charged/refunded, signed result URLs, per-image errors). The mention of generate_screenshot and create_screenshot_set ties it to the sibling tools that produce the ids it consumes.

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 lifecycle guidance: call after generate_screenshot or create_screenshot_set, repeat until final is true, then switch to download_results. It also tells the agent how to block in place via waitSeconds, which is exactly the when/when-not/alternative routing the dimension asks for.

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