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

With no annotations provided, the description carries the full burden. It discloses several important behaviors: one DID occupies one watcher slot, private_key is only verified for this call and never stored, and watcher counts are displayed as unverified. These go well beyond a bare 'register interest' statement. It stops short of explaining error cases or the exact relationship between sig and private_key, so a score of 4 captures its strong but slightly incomplete transparency.

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 three sentences, each earned: purpose, behavioral effect, and security requirement/caveat. It front-loads the primary verb and resource. It is slightly dense, especially the third sentence, but not wasteful. A score of 4 reflects good structure with minor density.

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?

Given there is no output schema and no annotations, the description covers the security model, the one-slot-per-DID behavior, and the unverified-count caveat. However, it fails to explicitly clarify that sig and private_key are alternative ways to authenticate (the schema marks both optional, and the description says 'Requires a signature... pass private_key' without mentioning you could instead pass sig). This is a real gap for an agent deciding which parameter to provide. Thus it is not fully complete.

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 80% (4 of 5 params described), so baseline is 3. The description adds meaning to the undocumented coord param by placing it in the canonical watch payload, and clarifies that private_key is an alternative to supplying sig (the server verifies the key). It also explains the ts validity window. This is meaningful added value over the schema, justifying a 4 rather than 3.

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 opens with 'Register interest in a coordinate' which is a clear verb+resource statement, and adds 'presence signalling without message passing' to clarify the domain. It does not explicitly name sibling tools for differentiation, but the tie to 'sweeps report the watcher count' distinguishes it from message-passing or reputation tools. A score of 4 reflects clear purpose with minor room for explicit sibling comparison.

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 explains what the tool does and mentions that sweeps report watcher counts, but it never states when to use this tool versus alternatives like drop or contradict. There is no explicit 'use this when you want to be counted as present' or any exclusionary guidance. This leaves an agent to infer the appropriate context from the schema and sibling names.

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