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

With annotations already declaring idempotentHint=true and destructiveHint=false, the description adds real context: the secret never leaves the machine, keys are sealed per UTC day, non-key holders see ciphertext, and re-calling re-sends today's keys. It does not spell out auth requirements or whether 'forget' is reversible, but it goes well beyond the annotation set. Minor tension exists between destructiveHint=false and 'forget (remove your key)', but re-registration is possible, so it is not a hard contradiction.

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?

One front-loaded sentence establishes what the tool is, followed by the required input, then the outputs and the re-call/forget behavior. It is dense with pricing tiers and SDK jargon, but every clause carries information and nothing is padded.

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 and no required parameters, the description correctly fills the gap by naming the return values (holder id, stream URL, decode command) and the state-changing behavior of re-calls and forget. Combined with annotations covering idempotency and safety, an agent has enough to invoke it correctly; only auth/permission prerequisites are omitted.

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%, so the baseline is 3, but the description adds meaning the schema does not: that 'x25519' is a public key whose private counterpart is generated locally via the SDK keygen command, and that register refreshes an existing registration. The action semantics (register/status/forget) are reinforced rather than merely restated.

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 states a specific action and resource: registering an X25519 public key to receive a paid, daily-sealed signal stream, with concrete outputs (holder id, stream URL, decode command). The purpose is unambiguous, though it is embedded in a dense, jargon-heavy sentence and never explicitly contrasts itself with siblings like watch_set or follow.

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 mode-level guidance ('Register...', 'Call again to have today's keys re-sent', 'action forget stops it') that mirrors the register/status/forget enum, so the when-to-use for each action is implied. There is no explicit statement of when NOT to use this tool or which sibling to pick instead, so guidance stops at implied usage.

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