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

No annotations exist, so the description carries the full burden and does reasonably well: it discloses exactly what is destroyed (results of done runs), the resulting post-state (each reads done with result: null, purged: true), and the side effect on quota. It omits irreversibility and permission/tenant requirements, but the mutation semantics are clearly conveyed.

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 dense sentence that front-loads the destructive action and then the state change and quota effect. No padding, though it is long and would read better split, but every clause carries information.

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 and no annotations, the description covers the key behaviors an agent needs: what is deleted, the resulting run state, and the quota benefit. It lacks any note on reversibility or required permissions, which is the main remaining gap.

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 both parameters are already documented. The description restates before_unix's cutoff semantics without adding syntax or edge-case detail, and never touches tenant_key, so baseline 3 applies.

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 (delete/purge) applied to a precise resource (stored results of done runs) with an explicit scope (finished at or before before_unix). The 'done run' qualifier distinguishes it from siblings like host.runs.cancel (running runs) and host.runs.get/list, so an agent can select it without opening schemas.

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 description explains the motivation ('Frees state_bytes_max quota') which implies when the tool is useful, but never states explicit when-to-use conditions or contrasts with alternatives such as host.runs.cancel or host.state.delete. Usage is inferable but not spelled out.

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