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

Goes well beyond the annotations: it states that sender_user_ids replaces the existing senders (not merges), that only supplied fields change, and — critically — that the returned 'verified' status covers only name and senders while stop rules and tracking come back not_readable and must be checked in the lemlist UI. That is exactly the kind of behavioral caveat annotations (destructive/openWorld) cannot convey.

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?

Front-loaded with the action and the field groups, then return-value caveats, then workspace semantics — a sensible order with no filler. A few clauses chain together densely, but every sentence carries information.

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 10-param mutation tool with an output schema, the description covers the mutation semantics, the partial-update rule, the sender replacement behavior, and the verification limitation of the response. It is nearly complete; only validate_only's dry-run behavior is missing, which matters for a destructive 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?

Schema coverage is 0%, so the description carries the full burden and largely does: it explains name, sender_user_ids (array replacing senders, sourced from lemlist_mailbox_health), the three stop_on_* flags, the two track_* flags, and the workspace optionality. Only validate_only and campaign_id are left unexplained, keeping it short of a 5.

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?

Starts with a specific verb+resource ('Einstellungen einer lemlist-Kampagne ändern') and enumerates the mutable fields, so the agent knows exactly what the tool touches. It does not explicitly contrast with siblings like lemlist_create_campaign or lemlist_pause_campaign/lemlist_start_campaign, leaving that differentiation to inference.

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?

Usage is implied by the field list and by 'Nur angegebene Felder werden geändert' (partial update semantics), and the workspace fallback is spelled out. However, there is no explicit when-to-use/when-not guidance versus lemlist_pause_campaign, lemlist_start_campaign, or lemlist_update_sequence_step.

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