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

readOnlyHint=true already tells the agent this is a safe read, so the bar is lower. The description adds real behavioral context beyond that: the content is generated from code and tied to a table with a code reference per entry, 'checked in every PR, not from memory', which signals authority and freshness. It does not describe pagination or response size, but for a single-enum lookup this is solid.

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?

It is front-loaded with the core definition in sentence one and the call-timing rule in sentence two, with no filler. The trailing enumeration of surfaces is redundant against the schema enum, which is the only real slack. Overall dense and useful.

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 must convey what comes back, and it does: the three lists (self-triggerable, manual-only, nonexistent) plus their code-backed provenance. For a single-required-param read-only lookup this is close to complete; only pagination/format details are absent, which is minor here.

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 100% and the single parameter carries a full 11-value enum, so the schema already does the work. The description's final sentence merely re-lists the same surface names already in the enum, adding no meaning beyond the schema. 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?

The description states a specific verb-and-resource: it returns the rules of one working surface, itemized into what an agent can trigger, what is manual-only, and what does not exist. That is far more specific than the title alone, and it is clearly distinguishable from the many lab_* list/get siblings. It stops short of naming a sibling to prefer or avoid, so 4 rather than 5.

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?

It gives explicit timing guidance — 'Call this BEFORE answering what is possible on a surface' — and names the failure mode it prevents ('saying that does not exist about something the editor can do'). That is strong when-to-use direction. It does not name an alternative tool or a when-not-to-call condition, so it does not reach 5.

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