update_instance

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

Annotations only say readOnlyHint=false and destructiveHint=true; the description adds the critical semantics that omitted fields retain their value, that the write is asynchronous (saved to the DB, applied later by the scheduler), and that the tool cannot confirm the change is live. That async-propagation caveat is exactly the kind of trait annotations cannot express.

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?

Four tight clauses, front-loaded with the mutation scope, followed by preconditions, the sibling alternative, and the async caveat in that order. No filler or repetition of the schema.

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 7-parameter partial-update mutation with no output schema, the description covers what changes, what is preserved, what gets rejected, and the fact that success is not immediately observable. An agent has everything needed to call it correctly and interpret the result.

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 each property already documents 'omit to keep', so the schema does the heavy lifting. The description reinforces the partial-update semantics at the tool level and names hostname implicitly as the lookup key for the target instance, adding modest but useful framing.

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 (Change) and resource (a registered instance), then enumerates the mutable fields (name, ports, HTTPS flag, server_name, method). It is immediately distinguishable from create_instance and delete_instances in the sibling list.

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 routes new hosts to create_instance and warns that unknown or read-only instances are rejected, which is real precondition guidance. It stops short of describing when an agent should prefer get_instance/list_instances first to verify state, but the usage context is clear.

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