create_message

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

No annotations are provided, so the description carries the full burden. It discloses that send/receive occurrence specs are automatically created, which is a useful behavioral detail. However, it doesn't mention prerequisites (e.g., lifelines must exist), whether the operation is reversible, or any side effects beyond the occurrence specs. For a create tool, this is adequate but not rich.

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?

Two concise sentences, front-loaded with the main purpose and a key behavioral side effect. No redundant words or irrelevant information. Efficiently structured for quick parsing.

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?

The tool is simple with only 4 parameters, and an output schema exists, so return values need not be described. The description covers the core behavior and side effect. It doesn't explicitly state that the lifelines and interaction must already exist, but that is implied by the operation. Overall, it's sufficiently complete for an agent to call it 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 0%, so the description must explain parameters. It clarifies that interaction_id refers to the containing Interaction, and sender_lifeline_id/receiver_lifeline_id refer to the two Lifelines. The name parameter is self-explanatory. The description effectively maps all four required parameters to their roles, though it doesn't add format or constraint details.

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 clearly states the verb 'Create' and the resource 'Message', and specifies the context: between two Lifelines in an Interaction. It also adds a distinctive detail (automatic creation of send/receive occurrence specs) that differentiates it from sibling tools like create_lifeline or create_interaction. No ambiguity or tautology.

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 implies when to use this tool: when creating a message within an interaction, as opposed to other creation tools. It doesn't explicitly name alternatives or state conditions to avoid, but the purpose is so specific that an agent can infer the appropriate usage. Missing explicit 'use this instead of X' guidance, but the context is clear.

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