create_message_share_link

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

The annotations only say readOnlyHint=false and destructiveHint=false, so they don't disclose much beyond 'this writes'. The description fills the gap by explaining what is created, what the `id` means for other tools, what fields can be returned, and what happens on a BAD_REQUEST with two specific causes. It also discloses that the full payload is much larger and suggests response_fields as a mitigation.

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 organized with clear section labels (USE WHEN, USE INSTEAD, FIRST, EXAMPLE, RETURNS, NARROW, ERROR) and front-loads the core purpose. Each section earns its place by conveying a distinct operational fact; despite the length, there is no filler or repetition of schema text.

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 7-parameter tool with no output schema, this description is remarkably complete: it explains prerequisites, alternatives, return shape, how to obtain dependent IDs, optional response narrowing, and error conditions. An agent can correctly select and invoke this tool using only the description plus the schema.

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?

Though schema coverage is 100%, the description adds critical parameter behavior: `message_id` is only needed when `share_type` is "forward", `shared_message_id` comes from `list_messages` results[].id, and `response_fields` is a dot-path allowlist for shrinking the response. The example ties required parameters together, and the error section clarifies invalid parameter combinations. This goes well beyond the raw schema descriptions.

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 first sentence names the exact verb and resource: "Create a shareable link to an existing message ... and get the URL back." It clearly distinguishes this tool from siblings like `add_attachments_to_message` by contrasting sharing a Carbon Voice message outward with attaching an external URL. The purpose is unambiguous and specific.

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 is exemplary in routing: it says when to use `share_type: "link"` vs `"forward"`, names the alternative tool `add_attachments_to_message` and when NOT to use it, and tells the agent to call `list_messages` first for `shared_message_id`. It even gives a concrete JSON example, leaving no ambiguity about invocation.

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