copy_message

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

With no annotations, the description carries the full burden and does so: it discloses the confirm gate ('No message is written unless confirm is true'), non-atomicity ('Kafka cannot retract a record produced before a later item failed'), permission requirements (destination must be writable), the read-only source allowance, and Schema Registry id translation warnings with the registry side effect of translate_schema.

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 core action and scope, then organized into confirm/atomicity, permissions, and schema-translation paragraphs. Dense with earning content, though slightly long for a two-parameter tool.

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?

Despite an output schema making return values optional to explain, the description adds result ordering ('Results follow items order, each carrying index with result or error') and the duplicate-item refusal rule. An agent has everything needed to invoke this correctly, including safety and side-effect context.

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 100%, so both top-level parameters and the nested item fields are already fully documented. The description reinforces confirm and items semantics ('one confirm covers the whole batch') and adds provenance-header behavior, but contributes no syntax or format detail the schema lacks, so the baseline 3 applies.

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 ('Copy 1 to 20 existing messages'), names the addressing scheme (topic/partition/offset) and the destination constraint. It is clearly distinguishable from siblings like get_message, produce_message, or search_messages.

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?

Explains the operating context well: batches are capped at 20, a single message is an array of length one, confirm gates any write, and list_clusters is named for resolving destination_cluster names. It does not explicitly contrast with produce_message for creating new messages, so it stops short of full alternative routing.

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