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

Annotations already declare readOnlyHint=true, so the description's 'Read' and 'No credit cost' add useful behavioral context beyond the annotation. It doesn't describe return format or pagination, but for a zero-parameter read tool with readOnlyHint, the description covers the key behavioral trait.

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?

Two short sentences with no wasted words. The core purpose is front-loaded, and the cost note is a valuable addition.

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?

For a zero-parameter read-only tool with readOnlyHint annotation, the description is nearly complete. It could mention what the response contains (e.g., numeric values) but the description's mention of credits used/reserved and limits gives enough context for an agent to understand the tool's purpose.

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?

The tool has zero parameters, so there is no schema burden. The description adds meaning by clarifying what is being read (credits used/reserved and limits) and that there is no credit cost, which is useful for an agent deciding whether to call it.

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 reads free beta credits used/reserved and limits, with a specific verb ('Read') and resource ('Free beta credits used/reserved and limits'). It is distinct from sibling tools, which are all document/job operations, so an agent can easily tell this is a usage/account query tool.

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 implies this is a read-only query tool for checking usage/limits, and the sibling list confirms it is the only usage-related tool. It doesn't explicitly state when to use it vs alternatives, but the context makes it clear there are no real alternatives for this purpose.

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