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

Annotations already declare readOnlyHint=true and destructiveHint=false, but the description adds non-obvious operational context: that credit changes are not possible here and must go through accounts with human involvement. It also instructs the agent to cite the returned numbers, which is behavioral guidance not captured anywhere in the structured fields.

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?

Three sentences, well front-loaded: return shape first, then the pre-spend trigger, then the read-only boundary. Minimal waste, though the 'when credit has come up' clause is slightly loose and 'cite the numbers' is an instruction rather than a description.

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?

With no output schema, the description still enumerates the returned fields and the scope of the lookup, and it covers the mutation boundary. Nothing an agent needs to call this correctly is missing.

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 100% and the single 'workspace' parameter already documents slug/default/override/API-key behavior fully. The description adds no parameter detail, so the baseline 3 applies.

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?

It names the specific resource (the workspace's inference-credit position) and enumerates exactly what is returned: plan, this month's grant and spend against it, and the purchased balance that overage draws on. No sibling tool covers credit, so the scope is unambiguous.

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?

It states the trigger condition ('before proposing spend-heavy work (eval runs, batch expansions) when credit has come up') and routes the agent elsewhere for the mutation path ('top-ups and plan changes happen in accounts, by a human'). Both when-to-use and when-not-to-use are explicit.

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