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

Annotations already declare the non-read-only, non-idempotent, non-destructive profile, so the description's job is supplementary — and it delivers the permission requirement plus the domain meaning of prepaid (an asset) vs promotional (free), which the agent cannot infer from structured fields. It stops short of saying what happens on a repeat call or whether an entry can later be corrected.

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?

Four short sentences, front-loaded with what is recorded, then kind semantics, then format, then permission. Nothing is padded, though the permission sentence reads as an afterthought rather than being integrated with usage guidance.

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?

An output schema exists, so return values need no explanation, and annotations cover the safety profile. Still, for a 6-parameter mutation tool with zero schema descriptions, the definition leaves provider enumeration, duplicate handling, and post-hoc editability unaddressed.

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?

Schema description coverage is 0%, so the description carries real weight and does explain the kind values and the YYYY-MM-DD date format for granted_on/expires_on. But provider's accepted values, the note field's purpose, and the effect of leaving expires_on null are left entirely to the schema's bare titles.

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 and resource: 'Records credits from an AI provider.' An agent can distinguish it from list_credits or credits_expiring by the write framing, but the description never names those siblings or explicitly contrasts with them.

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 permission prerequisite ('owner, admin or finance member') is useful context but is about authorization, not when to choose this tool over alternatives. There is no statement of when to record a credit versus, say, add_bill, leaving usage implied.

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