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

Annotations already declare readOnly, idempotent and non-destructive, so safety is covered. The description adds value beyond them: it discloses that the call is free, that it works for any job the account started (a scope/auth boundary), and what the failure result contains (the reason). It does not mention rate limits or polling guidance, keeping it from 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?

Two short sentences, zero waste, with the core semantics (what the read reports) front-loaded before the cost/scope note. Every clause earns its place.

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 usefully enumerates the possible terminal/working states, partially compensating for the missing return contract. Combined with annotations covering safety, an agent has enough to call it correctly, though the exact payload shape is still unspecified.

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?

Only one parameter and schema coverage is 100%, so the schema already defines the job id format (job_..., max length 128). The description adds nothing about the parameter, so the baseline of 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 (reads) and resource (a job) and enumerates the possible states it reports — working, done with links, failed with reason, cancelled — so an agent knows exactly what it returns. It does not, however, distinguish itself from siblings like ugcfans_wait_job or ugcfans_cancel_job, which an agent also faces when reasoning about job status.

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?

"Free. Works for any job the account started" gives useful scope and cost context, implying this is a cheap polling/status check. But it never says when to prefer this over ugcfans_wait_job (blocking wait) or ugcfans_cancel_job, leaving the routing decision to inference.

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