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

Annotations already declare readOnlyHint=false and destructiveHint=false; the description adds a genuine behavioral fact, 'requires write scope,' which tells the agent about auth prerequisites. It omits what matters most for a bulk write: duplicate handling/merge-vs-skip behavior, whether partial failures abort the whole import, and whether the 500-item limit is enforced server-side.

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 compact sentence, front-loading the bulk-import purpose with the optional campaign scope and the scope requirement appended. No filler or redundant restatement of the name.

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?

Adequate for a two-parameter tool, but this is a bulk mutation touching up to 500 records with no output schema, and the description says nothing about return values (created vs skipped counts), error modes, or idempotency. Those gaps matter more here than for a single-record create.

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 contacts, its nested fields, and campaign_id. The description only restates those two parameters at a high level and adds no meaning about tag semantics, campaign membership side effects, or dedupe behavior.

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?

States a specific verb and resource with scope: 'import multiple contacts at once, optionally adding them to a campaign.' This distinguishes it in spirit from single-contact creation and from add_campaign_contacts, but it never names those siblings, so differentiation is inferred rather than explicit.

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 phrase 'import multiple contacts at once' implies the bulk use case, and 'optionally adding them to a campaign' hints at the campaign variant. However, it gives no explicit when-to-use guidance versus create_contact for single records or add_campaign_contacts for contacts that already exist, and no when-not conditions.

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