List EMQX Subscriptions

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

Annotations already declare readOnlyHint, idempotentHint, and non-destructive behavior. The description adds value by specifying that it returns 'every subscription in the cluster' (cluster-wide scope) and explaining the powerful match_topic behavior. This goes beyond the annotation defaults without contradicting them.

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 two short sentences with no filler. The first sentence front-loads the core purpose, and the second delivers the most valuable filter behavior. Every word earns its place.

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 a rich schema covering all parameters, annotations providing safety metadata, and an output schema present, the description does not need to cover pagination or return details. The description's cluster-wide scope and match_topic emphasis round out the tool's purpose sufficiently for an agent to select and invoke it correctly.

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 provides 100% description coverage for all six parameters, including a detailed explanation for match_topic. The description's match_topic sentence is essentially a paraphrase of the schema text, so it adds no new semantic meaning beyond what the schema provides.

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 opens with 'Every subscription in the cluster, with filters,' which clearly states the verb (list) and resource (subscriptions) plus the cluster-wide scope. This distinguishes it from siblings like emqx_client_subscriptions, which are client-specific, and highlights the unique match_topic capability.

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 clear usage context by noting that match_topic should be used to determine which subscribers receive a message on a concrete topic. It does not explicitly name alternatives or exclusions, but the cluster-wide scope and the special callout for match_topic provide practical guidance for when to use this tool.

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