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

No annotations provided, so description carries full burden. It successfully discloses return structure (broken down by wallet vs subscription credits) and format (text summary), adding value beyond the schema. Lacks auth/rate limit details but adequate for simple read operation.

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?

Front-loaded with purpose first. Slight redundancy between 'Returns your current...' and 'Returns: A text summary', but overall efficient three-sentence structure with no extraneous 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?

Appropriate for a zero-parameter read operation. Despite having output schema (per context signals), description adds useful context about the credit breakdown structure thatschema likely doesn't convey.

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?

Zero parameters present. Per guidelines, baseline is 4 for zero-parameter tools. Description correctly implies no inputs needed via 'Check your...' phrasing.

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?

Clear specific verb ('Check') + specific resource ('maskr.io credit balance'). Distinguishes from siblings: get_credit_cost (pricing), get_packages/plans (offerings), and image processing tools.

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?

Clear what the tool does, but lacks explicit when-to-use guidance versus siblings like get_credit_cost. Usage is implied by the specific purpose but no explicit 'when not to use' or alternatives mentioned.

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