invoke_capability

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

With no annotations, the description carries the full burden and does well: it discloses the single-shot delegation model ('once per call — no retries') and the mutation risk ('read-only unless the target itself writes'). It leaves failure handling and auth prerequisites unstated, but the key behavioral traits an agent needs are present.

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 line that front-loads the purpose, then the delegation semantics, then the selection guidance. Every clause earns its place with zero padding.

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?

Given a nested-args escape hatch with a fully-described schema and no output schema, the description covers purpose, delegation model, retry behavior, and write risk adequately. Only error/response handling is left implicit, a minor gap against the rich schema.

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 the schema already documents name, args, workspace_dir, task_id, and request_id thoroughly. The description adds no parameter-level detail beyond what the schema provides, so the baseline of 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?

The description opens with 'Escape hatch: call a tool not listed above, by exact name' — a specific verb, resource, and mechanism. It distinguishes itself from the listing-focused siblings by making clear it is the fallback for tools not surfaced elsewhere.

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?

Explicitly states when to reach for it ('call a tool not listed above') and when not to ('Prefer listed tools'), which routes the agent away from it by default. It stops short of naming a concrete sibling alternative, but the guidance is clear and actionable.

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