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

Annotations already declare readOnlyHint, idempotentHint, and destructiveHint=false, and the description reinforces this with "Read-only: it cannot change a limit." It adds genuinely new behavioral context the annotations lack: an authentication requirement ("needs your API key") and a cost note ("Free"), plus field semantics such as "paused = emergency stop." That is useful but limited to a few phrases rather than a full behavioral picture.

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?

The core scope is front-loaded in the first clause, and the closing sentences carry the when-to-use and access constraints. It is dense — a packed list of returned fields and parenthetical glosses — but every clause adds information rather than restating the name.

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 carries the full burden of describing return values, and it does so concretely: caps, spent/remaining today, scopes, expiry, balance, and allowance details including pause/expiry states. It also covers the access prerequisite and read-only guarantee, leaving nothing an agent needs in order to call it correctly.

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 takes zero parameters, so there is no schema-level semantics for the description to compensate for; this is the expected baseline. No parameter detail is needed or missing.

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?

Opens with a specific framing ("What your API key may still spend") and enumerates the exact resources returned: daily and per-request caps, spent/remaining today, scopes, expiry, account balance, and Base/Solana allowance limits. An agent can distinguish this from siblings like get_balance or get_allowance because the scope is explicitly account-level aggregate state, not a single value.

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?

Gives an explicit trigger: "Use before a paid call to see whether it fits," which tells the agent when to reach for it. It does not name alternatives or exclusions (e.g. when get_balance alone would suffice), so it stops short of a full routing rule.

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