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

Annotations already flag destructiveHint=true, but the description adds specific behavioral warnings: 'CHANGES WHERE YOUR DATA IS SENT when the routing or config is edited' and clarifies that pausing does not delete history. These go beyond the generic destructiveness hint, informing the agent of concrete side effects. No contradiction with annotations; the description enriches them.

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, front-loaded with the primary actions and then the crucial side-effect warning. No fluff or repetition. Every sentence adds distinct information – the first lists operations, the second warns about data routing and pause semantics. Highly efficient for an agent scanning for intent.

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?

The tool has a nested routing object and an output schema (provided), so return values are covered elsewhere. The description explains the key side effects (data routing changes, pause behavior) and implies the tool modifies an existing destination. It does not mention prerequisites like permissions or existence, but these are typically implied for update operations. Given the annotations and schema, the description is complete for correct invocation.

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% – each parameter (id, name, routing, isActive) has a clear description. The tool description restates these actions ('Rename', 'pause or resume', 'change routing rule') without adding new syntax or format details. Since the schema already documents parameters thoroughly, the description adds minimal semantic value beyond a high-level summary. Baseline 3 is appropriate.

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 clearly states the tool updates an existing destination by renaming, pausing/resuming, or changing routing. It distinguishes from sibling create_destination (which adds new) and list_destinations (which lists) by focusing on modifications. The verb 'update' plus the enumerated actions make the purpose unambiguous.

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?

The description implies use for existing destinations by mentioning rename, pause/resume, and routing changes. It does not explicitly name alternatives like create_destination for new entries, but the context of modifying an existing destination is clear. Pausing behavior is explained as stopping delivery without deleting history, which provides usage context. However, it lacks explicit 'when not to use' or direct comparison to siblings.

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