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

Annotations already declare readOnlyHint=true and destructiveHint=false, so safety is covered. The description adds useful context by describing the three reachability mechanisms it returns and the call-once semantics, but since no output schema exists it could say more about what the response actually contains (e.g. code snippets per platform).

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?

Two dense sentences plus a reference URL; purpose and usage are front-loaded and there is no filler. The doc link is the only arguably optional element.

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 read-only, zero-required-parameter helper with no output schema, the description covers what it returns conceptually and when to invoke it. Remaining gaps are the platform parameter's meaning and the exact return shape.

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 description coverage is only 50% (worker is documented, platform's enum is not), and the description never mentions either parameter. With low coverage the description should compensate, but it offers no guidance on the worker or platform inputs beyond the schema's own text.

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 action (return reachability setup instructions) and enumerates the three mechanisms it covers: Tango Runner, webhook, and check_in/heartbeat polling. Clear that it returns instructions rather than performing polling, though it doesn't explicitly contrast itself with sibling tools like set_webhook or check_in.

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?

"Call this once when you connect, or whenever Tango tells you you are unreachable" gives explicit timing guidance and a trigger condition. It does not give a when-not-to-use or name an alternative tool, but the usage context is unambiguous.

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