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

Annotations already cover the safety profile (readOnly, idempotent, non-destructive), and the description layers on the parts annotations cannot express: the ten-minute hold ceiling, the covered: true/false outcome states, the same-arguments retry contract, and a conversational rule about not naming tools to the person. That is substantive behavior beyond structured fields.

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 blocking condition is front-loaded and every clause carries operational meaning. The parenthetical '(the waiting_for_credits answer says where)' and the trailing 'Never name a tool to the person' are slightly awkward insertions, but nothing is redundant enough to penalize heavily.

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 explains the return states (covered: true/false), the failure path, and the retry loop, which is exactly what an agent needs to drive this tool correctly. Nothing material about invoking or interpreting it 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 coverage is 100%, and the schema already explains that hold_id comes from the waiting_for_credits answer and that timeout_seconds defaults to the hold's remaining life. The description adds no syntax or format detail beyond that, so the baseline 3 applies.

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 names a concrete verb+resource behavior: it holds until a person adds the credits a previously-blocked call needs, then answers covered: true. It explicitly anchors its purpose to the waiting_for_credits response, which no sibling tool replicates, so an agent can tell it apart from request_budget, call_tool, and run_tools.

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?

It gives explicit sequencing rules: call it immediately after telling the person how many credits are needed, call the original tool again with the same arguments when covered is true, and follow the message without retrying when covered is false. Both the when-to-use and when-not-to-retry branches are stated outright.

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