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

With no annotations, the description carries the full burden of behavioral disclosure. It does add one important trait beyond the schema: that only passed fields are modified (partial-update semantics), which helps distinguish PATCH-like behavior. However, it omits permissions, validation rules, whether explicit null clears a field, and the consequences of changing campaign state.

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?

A single front-loaded sentence with zero waste. The partial-update caveat is placed immediately after the core action, making the key information easy to find.

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 12-parameter mutation tool with no annotations, no output schema, and no parameter descriptions, a one-sentence description is far too thin. It covers the basic action and partial-update behavior but leaves critical gaps around parameter meanings, validation, and permissions.

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 0%, so the description should compensate, but it provides no meaning for any of the 12 parameters. The clause 'only passed fields are modified' gives generic semantics for optional parameters but says nothing about name, dates, trigger_type, url_patterns, message_content, or the required bot_id/campaign_id identifiers.

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 and resource ('Update an existing campaign'), which clearly sets it apart from create_campaign, delete_campaign, and list_campaigns by action type. It does not explicitly name those siblings, but the operation is 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?

There is no explicit guidance on when to use this tool versus create_campaign, delete_campaign, or list_campaigns beyond the implied context of modifying an existing campaign. No prerequisites, permissions, or exclusions are mentioned.

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