Get an ESPHome device's LVGL pages

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

Annotations already declare readonly/idempotent/non-destructive, so the safety profile is covered. The description goes beyond that by disclosing the mechanism (parses the device YAML) and the error contract (`{"error": ...}` when the file is missing/unparseable or there is no `lvgl:` section), which is genuinely useful behavior an agent cannot infer from structured fields.

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?

Well front-loaded with a clear lead sentence, then labeled Use when / Not for / Returns / Errors sections that are easy to scan. The Returns block largely restates the existing output schema, a minor redundancy, but every other sentence 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?

For a single-param read tool with an output schema and full annotations, the description covers purpose, routing, mechanism, return shape and error cases. An agent has everything needed 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?

There is a single `device_name` parameter with 100% schema description coverage (including the '.yaml'-optional note), so the schema already does the heavy lifting. The description adds no parameter-level meaning beyond what the schema states, 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 ('Get the LVGL pages configured on an ESPHome device') and further specifies exactly what it reads: the `lvgl:` section's `pages` and `displays[0].default_page`. It clearly distinguishes itself from the sibling `esphome_lvgl_get_page_widgets`, so an agent can route correctly without opening 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?

Explicit 'Use when' names the concrete preconditions (getting page IDs, background colors, widget counts before drilling in) and 'Not for' names the exact alternative (`esphome_lvgl_get_page_widgets`) with the condition that selects it. Nothing is left to inference.

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