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

Annotations already declare readOnlyHint=true, idempotentHint=true, and destructiveHint=false, covering the safety profile. The description adds one genuinely useful behavioral fact beyond that — the call does not consume credit — but says nothing about auth expectations, rate limits, or response shape.

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?

It is a single compact phrase with no filler and the distinguishing detail (no credit consumed) placed immediately. It is arguably too terse to stand alone as a sentence, which keeps it from a 5.

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 one well-documented parameter, safe annotations, and no output schema, the description is adequate for calling the tool. It hints at the return value (remaining credits) but gives no sense of the response shape, so it is minimum viable rather than complete.

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?

There is a single parameter (api_pass) and schema description coverage is 100%, with the schema explaining the mat_<hex>_<hex> format and how to obtain it. The description adds no parameter meaning at all, 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?

The description names a specific quantity (remaining MAT read credits) and a key property of the operation (does not consume credit), so the agent knows what comes back. It does not differentiate itself from adjacent credit/billing tools such as api_access, api_access_buy, or billing, so it stops short of a 5.

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?

There is no when-to-use guidance, no statement of prerequisites, and no routing to alternatives like api_access_buy for purchasing more credits. The implied use case (check balance before spending) must be inferred entirely.

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