Arc Status

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

Annotations already mark the tool as read-only, idempotent, and non-destructive, lowering the description's burden. The description adds value by spelling out exactly which state facts are reported, including the no-tab_id default and cross-run tab counts. There is no contradiction with the annotations.

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?

A single front-loaded sentence states the verb and resource first, then lists the key outputs. Every phrase contributes a distinct piece of information with no filler or redundancy.

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 status tool, the description plus annotations cover the essentials: the agent knows it is safe, idempotent, and what categories of state it will receive. The explicit itemized report list mitigates the lack of an output schema. Exact return formatting is unspecified, but that is not critical for correct invocation.

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?

With zero parameters, the schema fully covers the input surface and there are no parameter semantics to clarify. The baseline of 4 applies because the description does not need to compensate for any schema gaps.

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 uses a specific verb ('Report') and names a precise resource ('Arc state'), then itemizes four concrete data points. This distinguishes it from sibling tab and space tools that perform actions or list individual resources. The only minor ambiguity is the phrase 'previous run of this label,' but the overall purpose is unmistakable.

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 clearly conveys that this is a status/diagnostic call rather than a tab manipulation operation. The enumerated items imply the triggering situations: checking ownership, default tab resolution, and leftover counts. It does not explicitly name alternatives or exclusions, so it stops short of a 5.

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