Describe an IoT topic rule

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

Annotations already declare readOnlyHint=true, idempotentHint=true and destructiveHint=false, so the safety profile is covered. The description adds genuine behavioral value beyond them by surfacing the silent-message-loss semantics of a missing error action and noting the tool flags it — useful context an agent cannot infer from the annotations.

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 sentences, no filler. The return-shape enumeration is front-loaded and the second sentence earns its place by explaining a real operational hazard.

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 adequately covers the return shape by naming the fields returned. Annotations cover safety. The only gap is error behavior when rule_name does not match an existing rule, which is not addressed.

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?

Single required parameter with 100% schema description coverage ('Exact topic rule name'), so the schema already carries the semantics. The description adds nothing about name format, case sensitivity, or lookup failure behavior, so the baseline 3 applies.

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?

Specific verb+resource ('Returns one topic rule in full') that also enumerates the exact payload: SQL, SQL version, each action with its write target, and the error action. The 'one' clearly differentiates it from the sibling list_topic_rules without needing the schema.

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 by 'Returns one topic rule' (look up a single rule by name), but there is no explicit when-to-use, no mention of when-not to use it, and no routing to siblings such as list_topic_rules for enumeration. Minimum viable context, nothing misleading.

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