mqtt_subscribe

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

With no annotations, the description carries the burden of explaining behavior. It discloses that the tool returns a subscription ID and that messages are retrieved via polling, which is valuable. Still, it omits important behavioral details such as whether the subscription persists, whether it must be cleaned up, or what happens if the connection is lost.

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 extremely concise, with exactly two sentences. It front-loads the action ('Subscribe to MQTT topic pattern') and then provides the key return value. Every word earns its place with no filler.

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?

Although the tool is simple (one parameter) and an output schema exists, the description lacks essential context about prerequisites (e.g., connection requirement), lifecycle behavior, and how the returned ID should be used. The information gap is significant enough to limit correct invocation without prior knowledge of MQTT or the system.

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 has one param (topic_pattern) with 0% description coverage, and the description does not explain what constitutes a valid topic pattern (e.g., wildcard syntax, MQTT topic rules). The param name is self-explanatory at a basic level, but the description fails to add the necessary detail for correct usage.

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 uses a specific verb ('Subscribe') and resource ('MQTT topic pattern'), making the action unambiguous. It also differentiates itself from siblings like mqtt_connect and mqtt_disconnect by clearly focusing on the subscription lifecycle rather than connection management.

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 usage by describing that it returns a subscription ID for polling messages, which suggests it should be used after establishing a connection. However, it does not explicitly state when to use it relative to mqtt_connect or whether an active connection is required, leaving the usage context mostly implied.

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