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

Goes well beyond the annotations by disclosing the plan-limit failure (403 plan_limit_reached), the eligibility conflict shape (409 with details.state/details.blockers), the slug-minting side effect on first publish, the returned public.ar_url and public.embed_url, and the required scope: publish_items. The idempotency_key note is consistent with idempotentHint=false (not inherently idempotent, but a key makes retries safe).

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?

Front-loaded with the core action and dense with genuinely useful information; every clause carries an error code, precondition, or return field. The single dense block is a bit run-on but wastes little.

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 still conveys the salient return fields (public.ar_url, public.embed_url), all known error paths, the auth scope, and the precondition check. Nothing an agent needs to invoke it correctly is missing.

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?

Schema description coverage is 100%, so both parameters (id and idempotency_key) are already documented in the schema. The description adds no parameter-level syntax or format detail beyond what the schema provides, making the 3 baseline correct.

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 ('Publish the item's public AR page') and immediately clarifies the state transition ('Makes the item public'). An agent can distinguish it from unpublishItem without opening any schema.

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 a clear precondition ('Check item.publishable before calling') and explains the API-created-item default ('items created via the API start private'). It does not explicitly name unpublishItem as the inverse operation, so routing guidance is strong but not exhaustive.

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