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

Beyond the annotations (which already declare readOnly/idempotent/non-destructive), the description adds substantial operational context: no GPU time and no charge, it runs as the connected account via OAuth or connector API key, every call is rate-limited per key, and a 429 carries retry_after_s to wait on. It also explains how to interpret diagnose.tell_user output, which the agent could not infer from the schema alone.

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 purpose and pre-flight use case are front-loaded in the first sentence, and every subsequent sentence adds operative detail (thresholds, auth, rate limits, how to relay diagnose output). It is a single dense paragraph of roughly 150 words, which is longer than strictly necessary but not padded.

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?

An output schema exists, so return-value structure need not be restated, and the description still adds interpretation guidance (workers_available, gated, diagnose.tell_user). Combined with the disclosed cost, auth, and rate-limit behavior, an agent has everything needed to call and act on this tool 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?

The tool takes zero parameters, so the baseline is 4 and there is nothing the description needs to compensate for. Schema coverage is reported at 100% and no parameter semantics are missing.

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 names a concrete resource (connection/service status) and enumerates what it returns: server URL, GPU worker availability, queue length, expected wait, key usage. It is clearly a pre-flight/service-status check rather than a job-status tool, but it never explicitly contrasts itself with siblings like render_status or render_estimate, leaving that distinction to inference.

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 triggers are given: use it before the first render, when renders seem stuck, or to decide whether to route a render here, with a concrete decision rule (workers_available > 0 → preview in seconds; gated → gate gives typical wait). There is no stated when-not condition and no sibling tool is named as the alternative, so it stops short of a 5.

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