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

Annotations already declare readOnlyHint=false, destructiveHint=false, idempotentHint=true, openWorldHint=false. The description adds significant behavioral context: it discloses that unknown keys, owner/assignee ids, and money-lifecycle fields are refused; that pipeline stage must be open (never won/lost); that idempotencyKey is required to prevent duplicates; and that CRM field values are untrusted user content. This goes well beyond the annotations and gives the agent a clear model of the tool's behavior and constraints.

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 description is compact and front-loaded: the first sentence states the core action, then constraints are listed in a logical order (data validation, pipeline rules, custom fields, idempotency, return value, security note). Every sentence earns its place; no fluff or repetition of schema details.

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 create tool with 4 parameters, no output schema, and nested objects, the description covers the essential behavioral rules: required idempotencyKey, data field validation, pipeline stage constraints, customFields placement, and the return shape. It also warns about untrusted content. The only minor gap is that it doesn't explicitly state that objectType is the CRM object type, but that is inferable from the schema pattern and the sibling context. Overall, an agent has enough to call this correctly.

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 only 25% (only workspaceId has a description). The description compensates by explaining the semantics of `data` (field names from describe_object, customFields location, refusal of unknown keys), the pipelineId/pipelineStageId pairing, and the idempotencyKey requirement. It doesn't explicitly describe objectType or workspaceId, but the schema already covers workspaceId and objectType is fairly self-explanatory. The description adds meaningful meaning beyond the schema, though it could have explicitly mentioned objectType.

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 ('Creates one record') and resource, and distinguishes it from siblings like update_record and delete_record. It also clarifies the scope (one record, not bulk) and the object type context, so an agent can tell it apart from create_activity, create_task, create_custom_object, and create_pipeline.

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 gives explicit when-to-use guidance: it explains the pipeline placement rule (deal/lead requires pipelineId and pipelineStageId together), the idempotencyKey requirement, and the customFields location. It also implicitly distinguishes from update_record by focusing on creation and from create_activity/create_task by the objectType parameter. It even warns about untrusted CRM field values, which is a usage caution.

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