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

Annotations already declare destructiveHint=true and readOnlyHint=false, so the safety profile is covered. The description adds value beyond that by disclosing the session-locking side effect (create_ise_session returns 409 until closed) and the settling/terminal nature of the call, though it never explains what 'settle' entails financially or state-wise.

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?

Three short sentences, zero filler, with the core action front-loaded and the operational consequence placed last where it is most useful.

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 no-required-param, no-output-schema teardown tool, the description covers purpose, timing, and the cross-tool side effect. Missing only minor details like idempotency on repeated calls or whether settlement has irreversible effects, which would matter for a destructiveHint=true operation.

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 100% and both parameters (auth_token, payment_signature) are fully documented in the schema, including the x402 challenge flow. The description adds nothing about parameters, so the baseline 3 applies.

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 clear verb+resource ('End your active ISE session and settle it'), which is unambiguous about the operation. It does not explicitly contrast with the sibling end_sdac_session, so differentiation relies on the agent recognizing the ISE vs SDAC naming.

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 when you are done' gives direct timing guidance, and the 409 SESSION_EXISTS consequence of create_ise_session explains why the session must be closed before starting another. No explicit when-not or alternative-tool routing is provided, so it falls short of a 5.

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