tvh_epg_coverage

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

Annotations already declare readOnly/idempotent/non-destructive, so the description's job is to add the non-obvious traits — and it does: a 500-channel cap, disabled channels only appearing on explicit selection, overlapping events de-duplicated, and errors surfaced instead of silently under-reporting. Minor omission: it doesn't say whether an out-of-range 'hours' value errors or is clamped.

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?

Six short clauses, front-loaded with the core action and the window size, then layered scope rules and finally the exclusions. No sentence is redundant with the schema or annotations.

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?

An output schema exists so return values need no explanation, and both parameters get meaningful treatment. The only real gap is edge-case handling for out-of-range hours and what a partial-coverage result looks like, which an agent auditing gaps would want.

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 0%, so the description must carry the meaning — and it does, supplying the 1..168 hour range that the bare integer schema lacks and explaining that channel_uuids defaults to enabled channels only while an explicit list also picks up disabled ones. It leaves the UUID format/dtype guidance implicit.

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 ('Measure') and precise resource ('time coverage, gaps and description presence') for a bounded time window. The closing line explicitly rules out adjacent concerns (tuning a receiver, proving reception quality), which separates it from siblings like tvh_probe_reception and tvh_search_epg.

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 clear operating context: default scope is all enabled channels, explicit selection flips to include disabled ones, and the 'does not tune a receiver or prove reception' clause tells the agent when a different tool is needed. It stops short of naming the specific alternative tools for those cases, so it is not a full when/when-not mapping.

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