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

Annotations already establish that this is a non-read-only, non-destructive mutation. The description adds an important behavioral trait beyond the annotations: it is a PATCH-style update, and unspecified fields remain unchanged. This is genuinely useful for the agent.

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 a single front-loaded sentence that conveys the core behavior immediately. Every word earns its place; there is no filler or redundant repetition of the tool name.

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 9-parameter update tool, the schema and output schema already document all parameters and return shape. The description adds the one missing behavioral fact — only changed fields need to be included — making the definition complete enough for an agent to invoke it correctly.

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 schema has 100% parameter description coverage with excellent provenance hints (e.g. IDs sourced from list_clients, list_folders, list_users, list_themes, list_domains). The description itself adds only the partial-update semantics, but that is exactly the key cross-cutting parameter behavior the schema cannot convey per-field.

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 ('Update'), a specific resource ('an existing client'), and the key semantic of partial updates. It clearly distinguishes this from create_client, archive_client, and get_client without requiring the agent to open the schema.

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 phrase 'existing client' clearly implies this tool is for modifying already-created clients, and 'only include the fields you want to change' gives a clear usage pattern. It does not explicitly name alternatives or exclusions, but the context is clear enough for correct selection.

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