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

Annotations cover the destructive read/write hints, but the description adds crucial context annotations can't convey: this is not a sign-out, the Signal desktop app remains signed in, and the change is irreversible from the tool surface. That is exactly the extra behavioral detail an agent needs before a destructive call.

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 critical facts are front-loaded in the first clause, and every sentence carries information (effect, re-enable path, no sign-out, irreversibility). The UI path description is somewhat long and embedded mid-sentence, slightly reducing readability, but nothing is filler.

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?

An output schema exists, so return values need no explanation. For a zero-required-parameter destructive toggle, the description covers effect scope, reversibility, and the recovery path — everything an agent needs before calling.

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 both parameters (an optional account, an ignored confirm flag) are documented in the schema itself. The description adds nothing about parameters; it only notes Signal has one account implicitly. Baseline 3 applies when the schema does all parameter 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?

States a specific verb and resource ("Turns Signal off in Local MCP") and immediately clarifies the mechanism (tools stop reading it). It is unambiguous against siblings like signal_connect or slack_disconnect, and the scope of the effect is spelled out.

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?

Explicitly frames when this is appropriate versus when re-enabling is needed, and routes the user to the exact UI path (LMCP icon → My apps → app row → Read · Send · Write). It also warns that no tool performs the reverse operation, so the agent knows not to look for a signal_reconnect sibling.

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