get_rate_limit_status

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

Annotations already establish readOnlyHint=true/openWorldHint=false, and the description goes further by disclosing the shared budget semantics, cross-client counter behavior, the last-minute activity heuristic, and that this call is free against the budget. These are genuinely useful behavioral traits beyond 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?

The key facts are front-loaded and the description is short. The first two sentences restate the same action ('Show today's Marvin calls' vs 'Show how many Marvin API calls have been made today'), a minor redundancy that keeps it just under 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?

An output schema exists, so return values need no prose explanation, and the description covers budget semantics, sharing, and cost. Complete enough for a no-arg monitoring tool; only the absence of explicit usage-trigger guidance keeps it from a 5.

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 are zero parameters, so per the rubric the baseline is 4. The description correctly implies the tool takes no arguments, leaving nothing for the schema to add.

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 opening sentence states a specific verb and resource — showing today's Marvin API call count against a budget plus the last call time. This is a distinct monitoring tool with no realistic sibling overlap, so an agent can identify it immediately.

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 supplies clear operational context (check the shared 1440/day budget, detect other active clients within the last minute) but does not explicitly frame when to call it versus continuing work, nor any 'do not use' conditions. Usage is strongly implied rather than stated as routing rules.

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