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

No annotations are provided, so the description carries the full burden. It usefully discloses that keys are 'observed' (empirically discovered from RUM traffic rather than a fixed enumerated schema) and that they are session-scoped, but says nothing about whether results are cached, how fresh they are, or whether the listed keys are environment/time-range dependent.

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?

A single sentence with the scope qualifier front-loaded before the domain and use case. No filler, no redundancy, and the key discriminating word ('session-level') appears early.

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 zero-parameter, read-only enumeration tool with no output schema, the description covers what the tool returns (session-level metadata key names) and its domain. The only material omission is any indication of how the returned keys relate to constructing filters or how they differ from event-level keys.

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?

The tool takes zero parameters, so there is nothing for the description to disambiguate; the baseline of 4 applies. The description does not need to explain any argument semantics.

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 (List) and a precisely scoped resource (session-level metadata keys observed in RUM for TrueCoverage filters). The 'session-level' qualifier implicitly separates it from the sibling get-truecoverage-event-metadata-keys, but the sibling is never named, so differentiation is left to inference.

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?

The phrase 'for TrueCoverage filters' hints at why the keys matter, but there is no explicit when-to-use, no prerequisites, and no direction to the event-level counterpart when a caller actually wants event metadata keys rather than session keys.

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