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

The read-only posture is reinforced ('changes nothing', writes 'refused here'), which matches the readOnlyHint/idempotentHint annotations. But most of the text then details behavior of operations this tool cannot perform — send batch_task_id, test sending to a real contact, resend preview/confirm and activation quota consumption — which is noise that could mislead an agent into expecting those actions. For a three-action read tool it should describe the read behavior (pagination, funnel window semantics) instead.

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 correct framing is front-loaded, but roughly half the text is spent documenting create/update/send/test/resend in detail for a tool that refuses them. That is not conciseness — it is wasted tokens that also increase the risk of an agent attempting an unsupported action.

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 read tool with no output schema, the description should focus on what list/get/performance return and how the funnel window behaves. `performance` is described well, but `list` pagination/sort semantics and `get` response content are not, while a large amount of space goes to irrelevant write paths.

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%, so the schema already documents every parameter, and the description's per-action param recap (page, per_page, status, search, campaign_folder_id, id, since, until) largely duplicates it. The one genuine addition is the explanation of what `performance` returns per step (sends reached, finished, reason codes), which gives meaning the schema lacks.

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 opening line is excellent: 'Read campaigns — this tool changes nothing' with explicit routing of writes to `campaigns_manage`. But the second sentence then restates 'Manage campaigns' and enumerates create/update/send/test/resend among its 'Actions', which contradicts the first sentence and the schema enum of list/get/performance. The net effect is a purpose that is stated clearly and then muddied in the same breath.

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?

Strong explicit exclusion: writes belong on `campaigns_manage` and are refused here. However it also instructs 'Call get_action_types first when building actions', which only makes sense for the write tool, and gives no guidance on when to choose `list` vs `performance` vs the sibling `show_campaign`.

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