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

The readOnlyHint annotation covers the safety profile, and the description goes beyond it by enumerating what the response contains (text, direction, status, timestamps) and citing the underlying REST call GET /messages/{id}, which usefully confirms the read semantics and data shape.

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 tight sentences with the core purpose front-loaded and no filler. The REST endpoint reference is mildly redundant for an agent but harmless and short.

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?

With no output schema, the description responsibly lists the return fields (text, direction, status, timestamps), which is the key missing piece of structure. Combined with the readOnly annotation and one fully documented param, an agent has enough to call it correctly; only alternative-routing guidance is absent.

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?

There is a single required parameter with 100% schema coverage ("Message id."), so the schema already carries the parameter documentation. The description only restates "by its id" and adds no format or sourcing guidance beyond the schema, fitting the baseline 3.

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 ("Get a single message by its id") and contrasts implicitly with the plural simpletexting_list_messages sibling by emphasizing "single." It's clear what the tool returns, though it never names a sibling explicitly to route between get and list.

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?

Usage is implied: retrieve one message when you have its id. There is no explicit when-to-use, when-not-to-use, or pointer to alternatives such as simpletexting_list_messages for browsing or simpletexting_evaluate_message for analysis.

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