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

Annotations already declare readOnlyHint=true, openWorldHint=false, and destructiveHint=false, so safety is covered. The description adds that the balance is for the agent wallet tied to the active uc_live_ API key, but it does not describe auth requirements, return format, or pagination behavior. With annotations covering the safety profile, this limited added context warrants a 3.

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 description is a single front-loaded sentence with no filler. Every word contributes to identifying the resource and its scope.

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?

For a simple read-only balance lookup with no output schema, the description states the returned resource ('Credit balance') and the scoping key ('active uc_live_ API key'), while annotations cover the safety profile. It is complete enough to call correctly, though it could clarify the requiredness of the apiKey parameter.

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 sole parameter is apiKey, and schema description coverage is 0%, so the description must carry parameter meaning. It adds that the key is a live 'uc_live_' key tied to an active session, which is useful, but it does not say whether apiKey is required, optional, or what format is expected. Partial compensation for a one-param tool lands at 3.

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 resource (credit balance of the agent wallet) and scope (behind the active uc_live_ API key), so the agent knows what it retrieves. It does not explicitly differentiate from siblings like ucode_agent_billing or ucode_credits_status, so it stops short of 5.

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?

There is no when-to-use guidance, no exclusions, and no named alternative among the many sibling balance/billing tools. The description only states what the tool returns, leaving the agent to infer when to select it over ucode_credits_status or ucode_agent_billing.

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