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

The description states 'Read-only and free', which aligns with the readOnlyHint annotation and adds the cost aspect. It also discloses that it 'takes no parameters and scopes to your own account', providing full behavioral context beyond the annotations. No contradiction with annotations.

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 exactly two sentences, front-loaded with the primary purpose. Every word serves a purpose: intent, usage timing, safety guarantee, parameter count, scope. No redundancy or filler.

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 this is a simple read-only tool with no parameters and an output schema present, the description covers all essential context: purpose, when to use, cost implications, parameter count, scope. The presence of an output schema means return value details are unnecessary per the rubric.

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?

With zero parameters and 100% schema coverage, the baseline is 4. The description explicitly confirms 'takes no parameters', which adds clarity beyond the empty schema. No need for further parameter detail.

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 clearly states the tool's purpose: 'Check your current credit balance and subscription tier'. This is a specific verb-resource combination that distinguishes it from the many other get_* tools in the sibling list, which deal with ideas, teams, b2b, market signals, etc. No ambiguity about what resource is being checked.

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 explicitly tells when to use: 'before running anything that costs credits' and 'to confirm you have enough budget for a claim, simulation or content run'. This provides clear context for invocation. It also implicitly scopes to the user's own account, indicating when not to use it (checking other accounts). No alternative tool exists in siblings, so no exclusion needed.

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