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

Annotations already declare readOnlyHint=true, destructiveHint=false and openWorldHint=true, so the safety profile is covered. The description adds value beyond that by disclosing the external dependency — the call is 'answered by the attached engine' and fails without one, with world.open as the remedy. It stops short of describing the returned schema shape, but the tool's whole output is 'a full schema' and no output schema is declared.

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?

Three compact sentences, front-loaded with the purpose and then the workflow position. The engine-prerequisite sentence is slightly compressed to the point of being terse, but every sentence carries distinct information and nothing is repeated.

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 read-only introspection tool with one required parameter, full schema coverage and no output schema, the description covers what the tool returns, when to call it, and the operational prerequisite. The only gap is that it doesn't explain how ambiguous tool names are resolved across toolboxes, which the schema's `toolbox` parameter hints at but does not connect back.

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%, and the `as` parameter in particular carries a long, self-sufficient description, so the baseline is 3. The tool description adds no per-parameter detail — it only reinforces that the whole point is to learn arguments, which duplicates the schema rather than extending it.

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: 'Full schema for one registered tool — its arguments, types and behaviour.' It also implicitly distinguishes itself from the sibling search_tools by positioning itself as the schema-fetch step. An agent can tell it apart from adjacent tools like use_tool or search_tools without opening any schema.

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?

Gives explicit sequencing: 'Use after search_tools locates it and before calling it.' It also names the alternative behaviour being avoided ('instead of guessing arguments') and states the prerequisite ('it needs [an attached engine]: world.open attaches one'). This is a genuine when/when-not with the enabling condition spelled out.

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