List PJSIP endpoints and registration state

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

Annotations already declare readOnlyHint, and the description adds meaningful context by explaining the returned data (device state, registration counts) and the fallback to chan_sip peers on older installations. It does not, however, describe the output format or potential quirks, so transparency is adequate but not exceptional.

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 two sentences, front-loads the core purpose, and then adds use cases and a fallback note. Every piece of information is useful and there is no redundancy.

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?

For a simple list tool with one optional filter and no output schema, the description covers return content (device state, registered contacts) and a behavioral nuance (chan_sip fallback). It lacks explicit output fields or examples, but given the tool's simplicity, it is sufficiently 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?

The schema has 100% coverage for the single 'filter' parameter, so the description does not need to add much. It doesn't provide extra meaning beyond the schema's description, but the high schema coverage makes the baseline of 3 appropriate.

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 clearly states the tool lists PJSIP endpoints with device state and registered contact counts, and explicitly ties this to common queries ('is extension 1001 registered', 'which phones are offline'). It distinguishes itself from siblings like asterisk_channels and asterisk_status by focusing on endpoint registration rather than calls or system status.

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 provides explicit use cases for the tool, which gives the agent a clear context for when to invoke it. However, it does not explicitly mention when not to use it or name alternative sibling tools for other tasks, so it stops short of a full 5.

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