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

The description discloses that fields are merged (not replaced), returns the full updated/created object, and is scoped to the active Space. This goes beyond the annotations (readOnlyHint=false, destructiveHint=false) by explaining mutation semantics and output behavior, though it doesn't cover permissions or rate limits.

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 three sentences, front-loaded with the core purpose, and every sentence carries meaningful information. There is no fluff or repetition.

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?

Given the tool's complexity with many nested fields and no output schema, the description adequately covers the core behavior, return object, and Space scoping. It could be more complete by pointing out dedicated sub-tools for fields like geo targeting, but these are already noted in the schema, and the description remains sufficient for an update 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?

The tool-level description adds the key merge semantics for the body parameter and mentions the space_id override. The input schema itself provides rich descriptions for many fields (67% coverage), including nested objects and enums, so the description doesn't need to restate them but adds some value about how parameters are applied.

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 identifies the tool as a partial update for campaigns with explicit merge semantics, distinguishing it from create/delete/get/list campaign tools. It also specifies resource scope (Space) and the ability to override the active Space.

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 provides clear context for usage, including partial update behavior and Space scoping. It names set_active_space as an alternative for switching Space, but does not explicitly state when not to use this tool (e.g., for dedicated field-specific setters like set_budget or set_geo_targeting), though those are referenced in the schema.

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