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

Annotations already indicate this is non-read-only, idempotent, and non-destructive. The description adds useful behavioral context by stating that only provided fields are updated and that the response returns the updated phase object. There is no contradiction with the annotations.

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?

Two short sentences with no redundancy. The action and target are front-loaded, the partial-update rule is stated compactly, and the return value is included without extra prose.

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 relatively simple update tool, the description covers what is updated, how partial updates work, and what is returned. The input schema already documents the required phaseId and enum, while annotations cover the safety profile. It does not address prerequisites or disambiguate from create/delete, but those are not critical here.

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?

With 0% schema description coverage, the description partially compensates by enumerating the updateable fields (name, description, objectives, phase type, order) and noting partial-update behavior. However, it does not mention the required phaseId parameter or clarify constraints like enum values or objectives array semantics, leaving meaningful gaps.

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 uses a specific verb ('Update') with a precise resource ('a campaign phase') and lists the exact modifiable fields. It is clearly distinct from sibling tools like create_phase, get_phase, delete_phase, and update_campaign.

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 clearly implies this tool is for updating an existing campaign phase, and it adds the partial-update rule ('Only provided fields are updated'). However, it gives no explicit direction on when to choose this over sibling tools such as create_phase, delete_phase, or update_campaign, nor does it state exclusions.

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