post_text_message_templates_merge

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

With no annotations provided, the description carries the full burden and handles it exceptionally. It discloses the surprising non-sending behavior, cites live verification, notes that no delivery or record is created, and specifies the exact returned shape ({"mergedTemplate": "..."}). This goes well beyond the schema and corrects a misleading name.

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 warning and behavioral verification are front-loaded, making the most critical information immediate. The description is slightly longer than strictly necessary due to the live-verification anecdote, but that detail earns its place because it substantiates the surprising non-send behavior.

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?

Given no annotations and no output schema, the description is remarkably complete: it explains what the tool actually does, what it does not do, the edge case it serves, and the exact return payload. An agent has enough to invoke it correctly and interpret the response without additional documentation.

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?

The schema already documents all parameters with 100% coverage, so the description does not need to restate parameter meanings. The description adds overall context for recipients but provides no new parameter-level semantics beyond what the schema already gives.

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 a specific verb and resource ('Merge a text message template with multiple recipients') and supplies the endpoint. It immediately differentiates the tool from actual send operations by asserting 'this does NOT send anything,' so an agent can distinguish it from siblings like create_text_message or post_templates_merge.

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 an explicit when-to-use condition: 'the edge case of one text greeting multiple recipients at once' as a preview/render utility. It also clearly excludes actual sending behavior, though it does not name the alternative send tool explicitly or spell out 'use create_text_message if you want to send.'

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