capacity_forecast

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

Annotations already declare readOnlyHint=true, so the safety bar is lower; the description adds genuinely useful context beyond that: nearfull is 85% of total, no clock is read, and the projection is pure arithmetic, plus the 'insufficient-data' fallback state. It does not discuss pagination or response shape, but those are minor here.

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?

Front-loaded with the [READ] marker and the core purpose, followed by the arithmetic caveat and an Args section. No sentence is wasted, though the Args block partly mirrors parameter names already visible in the schema.

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 does explain the key return concepts (daysToNearfull, 'insufficient-data') and the nearfull threshold. It is complete enough to call correctly, though it could say more about the usage payload returned by default.

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 must carry the parameter burden, and it does: both daily_growth_bytes ('observed daily growth in bytes; omit for a usage-only view') and target ('Ceph target name from config; omit for the default') get meaning and default behavior beyond the bare schema types.

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?

The description opens with a specific verb+resource: '[READ] Capacity usage + a deterministic days-to-nearfull projection.' No sibling tool (osd_df, pool_df, cluster_status) does capacity forecasting, so an agent can identify this tool's distinct role immediately.

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 states clear conditional context: passing daily_growth_bytes yields daysToNearfull, omitting it yields 'insufficient-data' and a usage-only view. It does not name competing siblings or exclusions, which keeps it at 4 rather than 5.

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