plc_list_io

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

Annotations already declare readOnly, idempotent, non-destructive and closed-world, so the safety profile is covered. The description adds genuinely new behavioral context by warning that results are observed bindings and may not reflect the full hardware inventory, which sets expectations about result completeness. It does not mention pagination or result shape, but an output schema exists to carry that.

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 short sentences, front-loaded with the core action and followed by the caveat; there is no filler. It is arguably under-specified rather than verbose, but nothing in it is wasted.

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?

For a simple list tool with an output schema and full annotations, the description covers purpose and data-completeness caveat. It leaves out routing versus sibling list tools and any mention of paging behavior, which are the main remaining gaps for an agent choosing among many plc_list_* tools.

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 description coverage is 67%: limit and offset are documented in the schema, while project_id is undocumented in both places. The description adds no parameter meaning at all, so with moderate coverage the baseline of 3 is appropriate.

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 and resource: 'Read declared variable-to-address bindings.' That is far more precise than the name alone and tells the agent it returns bindings rather than variables or hardware. It stops short of naming a sibling (e.g. plc_list_hardware or plc_list_variables) as the alternative, so it is clear but not fully differentiated.

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 only implied: the caveat 'not a complete hardware inventory' hints that plc_list_hardware should be used for physical inventory, but no alternative is named and no when-not condition is stated. The agent must infer routing from the sibling list rather than from the definition itself.

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