Plan usage and upgrade

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

Adds substantial context beyond the annotations: it explains why readOnlyHint=false even though the default call is a pure read — only start_trial=true mutates the account, and that mutation is a free no-card trial with no payment taken. It also discloses the local-install-only browser-opening side effect for open=true and that the hosted server returns the link instead, which is exactly the kind of environment-dependent behavior annotations cannot express.

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 what the tool returns, then behavior under each flag, in five tight sentences with no filler. Every clause carries an operational fact (quota, link, anytime, default read-only, trial mutation, browser opening).

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 only three optional parameters and no output schema, the description compensates by naming exactly what comes back: plan, per-quota remaining amounts, upgrade benefits, and the upgrade link. The mutation, environment, and payment semantics are all covered, leaving nothing an agent needs 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 the baseline is 3 and all three parameters are already documented. The description goes a step further by framing start_trial as an actual plan change with no payment and eligibility conditions, and by reiterating the local-vs-hosted semantics of open. It does not, however, clarify the `plan` slug parameter, which is the only parameter left unaddressed in prose.

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?

A concrete verb plus resource: it shows the current plan, remaining quota per quota type, what upgrading unlocks, and the upgrade link. That is specific enough to distinguish it from content tools like list_my_articles or get_profile. It never explicitly contrasts itself with the sibling `status` tool, so an agent must infer which of the two answers account-level questions.

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?

'Call it any time — not only after hitting a limit' gives clear positive usage guidance and removes the false assumption that a limit must be hit first. It also implicitly bounds scope by stating the tool never upgrades a paid plan or takes payment, directing that step to the user via the link. It does not say when to prefer `status` instead, which is the main remaining gap.

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