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

With no annotations, the description carries the full burden and does meaningful work: it discloses the per-unit cost, the batch cap, and the non-obvious guarantee that spending does not reduce rank or paid-tier qualification. It does not cover failure modes (insufficient balance) or auth expectations beyond the schema's key field.

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?

Two sentences, front-loaded with the core action and cost, followed by the rank guarantee and return values. Every clause carries information an agent needs; no filler or restatement of the tool name.

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 mutation tool with no output schema, the description compensates by naming the return values (new balance and sittings held) and explaining the billing side effect. The remaining gap is error/edge-case behavior (e.g. insufficient points, partial redemption), which an agent would still have to discover at call time.

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%, so all three parameters are already documented in the schema (including the 1-10 bounds on sittings). The description's '100 points each, up to ten at once' reinforces the schema's maximum rather than adding new semantics, so baseline 3 is appropriate.

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 ('Spends points on Lunara Agent Trial sittings') with concrete unit economics (100 points each, up to ten). It is cleanly distinguishable from earning/lookup siblings like lunara_mission_submit and lunara_register_lookup, though it never names a sibling to contrast against an ambiguous one such as lunara_trial.

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?

Usage is only implied: the agent infers it should call this when it wants to convert an existing points balance into sittings. There is no explicit prerequisite (e.g. minimum balance needed, what happens if points are insufficient) and no statement of when to prefer lunara_trial over this.

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