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

No annotations are provided, so the description carries the full disclosure burden. 'List' implies a read, but it never confirms read-only behavior, ordering, whether the list is paginated or bounded, or what a contact entry looks like; it also says nothing about the odd notification_message parameter's purpose for this action.

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?

One short, front-loaded sentence with zero filler. It is efficient, though its brevity edges toward under-specification rather than optimizing information density.

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?

The tool is simple — zero required params, full schema coverage, no output schema — so not much is needed. Still, for a listing tool with no annotations, the description omits any sense of what the returned contacts contain or how many, which an agent planning a follow-up 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 description coverage is 100% and the single optional notification_message is fully documented in the schema. The description adds no meaning beyond it, so the baseline 3 applies rather than a higher score.

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: listing players saved in the in-game Phone contacts. That is distinguishable from siblings like search_players or list_dm_threads in concept, but the description never explicitly contrasts them, so the agent must infer the boundary.

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?

No guidance on when to use this versus search_players (search by name) or list_dm_threads (conversations). There are no prerequisites, no exclusions, and no indication of what the contacts list contains relative to other player-listing tools.

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