capacity_runway

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

Annotations only give readOnlyHint=true; the description adds genuine context beyond them: the [READ] tag, full determinism ("No clock or randomness — same inputs, same answer"), and the explicit failure mode when growth data is absent. It stops short of describing return shape or limits, but for a read-only computation this is solid added value.

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?

The core purpose and the [READ] marker are front-loaded, and the Args block is compact and scannable. The determinism point is made twice ('No clock or randomness — same inputs, same answer' alongside 'Deterministic'), which is slight redundancy but not bloat.

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 steps in to name the key return notion (daysToFull) and the 'insufficient-data' outcome, plus cross-tool provenance for the required ID. It could say more about the forecast model or output fields, but an agent has enough to call this correctly.

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 0%, so the description carries the full burden and does: it gives units for daily_growth_bytes (bytes/day), explains that omitting it skips the forecast, identifies cluster_ext_id as coming from cluster_list, and clarifies that target defaults to the config value.

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+resource: a deterministic storage-runway (days-to-full) estimate for a cluster. This is clearly separable from siblings like cluster_utilization (current usage) or cluster_health (state), since the output metric here is a projected time-to-full rather than a snapshot.

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 explains the conditional behavior of daily_growth_bytes (supply it to get daysToFull, omit it and the forecast is 'insufficient-data'), which implies when the parameter is needed, but it never states when to reach for this tool over cluster_utilization/cluster_health or what prerequisites (e.g., a cluster must exist) apply.

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