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

With no annotations, the description carries the full burden and does most of it: it discloses the prepaid 24h window, that the control token is one-time and must not be shared, the credit charge, and the exact return fields (lifecycleId, plc_ token, covered expiry). It does not say what happens if a lifecycle already exists for the subject, nor what an insufficient-credit or failure response looks like, which keeps it below a 5.

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?

Four compact sentences, front-loaded with the action and return value, then usage boundaries, then the return contract, then the deprecation notice last. No filler or restatement of the name; the security warning and sunset date each earn their place.

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?

Only two simple parameters and no output schema, so the description must supply the return contract itself — which it does (lifecycleId, plc_ token, expiry, credits charged). It also flags the deprecation and removal date, so an agent knows to prefer the newer sibling, leaving nothing essential unstated.

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 are already documented; the description reinforces that symbol identifies the single "position subject" the bundle covers but says nothing about chain (e.g. whether omitting it defaults or errors). Baseline 3 is appropriate when the schema does the explanatory work.

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?

"Buy a 24h Position Lifecycle bundle for one position subject and return the one-time control token" gives a specific verb (buy), a specific resource (lifecycle bundle), its duration and its output. It explicitly contrasts itself with check_trade_safety (single guard) and with position_lifecycle op "begin", so an agent can place it among 20 siblings without opening a 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?

States the positive condition (an agent needs guard, execution-receipt and close steps in one prepaid window), the negative condition (not for a single guard → use check_trade_safety), a security rule (never share the token), and a deprecation routing rule (prefer position_lifecycle with op "begin"). Both alternatives and the selection criteria are named explicitly.

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