List IoT things

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

Annotations already declare readOnly, idempotent, openWorld and non-destructive, so the safety bar is covered. The description adds genuinely useful behavioral facts beyond that: the region scoping, newest-page-first ordering, and the constrained return shape (names and types only). It doesn't elaborate on page-size clamping or token expiry, which are only implied by the schema.

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?

Three tight sentences, front-loaded with the core action and scope, then usage, then the return-shape caveat. Every clause carries information with no redundancy.

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?

There is no output schema, so the description compensates by stating exactly what is returned ('names and types only') and where to get detail. Combined with annotations and full schema coverage, an agent has everything needed to call 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?

Schema coverage is 100%, so all five parameters are already documented in the schema, including the attribute_name/attribute_value dependency. The description restates the filter capability ('by thing type or by a single attribute name/value pair') but adds no syntax or format detail beyond the schema, making the baseline 3 correct.

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 ('Lists AWS IoT things') with scope ('in the configured region') and ordering ('newest page first'). It explicitly distinguishes itself from the sibling describe_thing by noting it returns names and types only.

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?

Gives a concrete use case ('discover thing names before inspecting a shadow') and routes to the sibling for detail ('call describe_thing for detail'). It stops short of naming when not to use it or listing other alternatives like search_fleet_index, so it is clear context without explicit exclusions.

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