Get Account Usage

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

Beyond the annotations (readOnly, idempotent, non-destructive), it discloses two non-obvious operational facts: the call consumes 0 units but still counts against the per-minute rate limit, and its scope is restricted to the key behind this connection. Those details materially affect how an agent budgets and paces its calls, which the annotation block alone would not convey.

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 compact sentences: the first front-loads what is returned, the second carries cost/limit/safety constraints. No filler, no restatement of the title, and every clause adds information an agent would otherwise have to guess.

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 zero parameters, full annotation coverage, and an output schema that documents the return shape, the description supplies exactly the missing layer: cost accounting, rate-limit impact, and key scoping. Nothing needed to invoke this correctly is absent.

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 nothing for the description to disambiguate and the baseline is 4. The description correctly avoids inventing parameter-like options (e.g., no account selector), reinforcing that the key identity is implicit in the connection.

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 ('Check the units left on the TweetAPI API key behind this connection') and enumerates the returned fields: available units, plan allowance, PAYG balance, and per-minute rate limit. That framing cleanly separates it from every sibling tool, which all fetch tweet/user/list/space content rather than account quota data.

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 makes the use case clear (check remaining quota, verify plan/PAYG state) and gives a decision-relevant fact — it costs 0 units — that tells an agent this call is cheap to make preemptively. It does not explicitly say 'call this before heavy searches' or name an alternative, but no sibling overlaps, so there is little routing ambiguity to resolve.

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