Message details

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

Annotations already declare readOnlyHint=true and openWorldHint=true, so the safety profile is covered without the description. The description adds genuine value by disclosing what comes back (delivery status progression, service used, failure reason), which matters because no output schema exists; it does not cover permissions, error behavior, or whether messages outside the account are resolvable.

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?

A single compact sentence that front-loads the resource ('One message') and then the returned information. No filler, though the fragment style omits a verb that would have made the action unambiguous at no real length cost.

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 one-parameter read-only lookup with no output schema, the description covers both what is fetched and what is returned, which is the main completeness risk here. Missing only usage routing and ID sourcing, which are minor for a tool this simple.

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 0%, but the single parameter (message_id, string, required) is self-evident and the description's 'one message' wording implicitly confirms a single identifier selects the record. It adds no format, prefix, or ID-source detail beyond the schema, so it is adequate rather than informative.

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 single, specific resource and enumerates the fields returned ('content and delivery: sent, delivered, read or failed, the service used, and why it failed'), so an agent knows this is a single-message detail fetch. It lacks an explicit verb and does not name which sibling (e.g. get_conversation, search_docs) it replaces, so it stops short of full differentiation.

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?

There is no when-to-use or when-not-to-use guidance, and no alternative tool is referenced. The 'one message' framing implies single-item lookup versus list-style siblings, but that inference is left entirely to the caller.

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