Get credit balance

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

Annotations already declare readOnlyHint and openWorldHint, so the safety profile is covered. The description adds meaningful behavioral detail beyond that: the credential tiers accepted and the concrete failure mode (PERMISSION_DENIED 403 for a plain inference key). It stops short of describing return shape, but adds real value.

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 sentences that front-load the resource and then the auth constraints. Slightly repetitive with two consecutive 'Needs ...' clauses, but every sentence 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?

For a zero-parameter read with no output schema, the description covers what is returned (balance, promo credits, consumption) and what credentials are required. Sufficient for correct invocation, though it could be more explicit about the account/workspace scope of the read.

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 per the rubric the baseline is 4. There is nothing for the description to compensate for, and the schema is trivially complete.

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 ('Read') and a precise resource set: credit balance, active promo credits, and consumption. This is clearly distinct from sibling cost/usage tools like get_usage, estimate_cost, and get_pricing, so an agent can select it without opening the 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?

The description gives access prerequisites (dashboard JWT or custom-tier superkey; Relay credential) but no guidance on when to prefer this over get_usage or estimate_cost. Usage context is implied by the resource, not made explicit.

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