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

With no annotations, the description fully covers behavioral traits: returns a signed bearer token, archive payload is complete and same schema as live, pass cannot widen freshness, and misuse yields a 402 with explanation.

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 description is front-loaded with the main action, has clear sections (returns, importance, price), and is generally succinct without unnecessary detail. Minor redundancy with 'NOT A PREDICTION' line.

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?

While the description covers the return value, constraints, and distinction from other tiers, it omits explanation of the payment_signature parameter and assumes default empty behavior, leaving a significant gap for a purchase tool.

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 description does not mention the only parameter 'payment_signature' at all, despite 0% schema description coverage. The agent has no guidance on what to provide or how to format it.

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 explicitly states 'Buy a 30-day unmetered pass to the SYGNL/47 archive tier' with a verb and resource, and distinguishes from siblings by noting the archive pass does not authorize live, 1m, or 15m routes.

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 implies usage for archive data access and clearly states the pass is not for live/fresh routes, returning a 402 if misused. However, it does not explicitly compare to other subscription tools like sygnl47_subscribe_live_30d.

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