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

Annotations already declare readOnlyHint=true, destructiveHint=false, idempotentHint=true. The description adds that it returns a 'non-publishing connectivity proof' and explicitly states it never creates an identity, Sup, or durable receipt, reinforcing the read-only and idempotent nature and providing context beyond the structured hints. This aligns with, rather than contradicts, the annotations.

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 with every clause earning its place. The trigger condition is front-loaded, followed by the return type and exclusion. No redundancy or 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?

For a zero-parameter, read-only probe with an output schema and rich annotations, the description fully covers the trigger, the nature of the return, and what the tool must never do. Nothing an agent needs to call it correctly is missing.

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 tool has zero parameters and an empty schema, so there is nothing for the description to clarify. Per the baseline for 0-param tools (4), no additional parameter explanation is needed or possible.

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 verb (probe) and resource (hosted Sup MCP endpoint) and ties it to a clear trigger ('when the user asks whether... reachable'). The explicit exclusion of creating an identity, Sup, or durable receipt distinguishes it from siblings like sup_agents, sup_call_card, and sup_receipt, which likely handle those operations.

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 a specific condition for use ('when the user asks whether the hosted Sup MCP endpoint is reachable') and adds a negative constraint ('never create an identity, Sup, or durable receipt'), which implies when not to use it. However, it does not name the alternative tool(s) for those excluded operations, so the guidance is clear but not fully explicit.

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