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

Annotations already declare readOnlyHint=false, destructiveHint=true and idempotentHint=true, so the description's added value is the scope statement that selection produces no media and does not touch Main. It does not explain what the destructive effect actually is (that an existing selection is replaced) or the role of request_key in idempotency, which is the main behavioral gap.

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?

Two sentences, front-loaded with the verb and resource, with the scope negation second. No filler, though the phrase 'native home access' is opaque jargon that costs clarity without adding meaning.

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?

An output schema exists, so return values need not be described, but the tool is a destructive, idempotent mutation with six required parameters and zero schema descriptions. The description says nothing about the concurrency/request-key contract, the meaning of file_id vs take_id, or how to recover from a revision mismatch.

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% across six required parameters, so the description must carry the load, yet it only obliquely maps to expected_revision ('exact file revision') and possibly workspace_id ('native home access'). file_id, take_id, request_key and the nested subject.kind/id are never explained in prose.

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 uses a specific verb ('Select') and resource ('an existing character, set or prop catalog take'), matching the subject.kind enum in the schema. It also draws a boundary by saying it 'Does not choose Main', which separates it from the element-main sibling, though it never names the sibling tools (native.select_element_take, native.set_element_main).

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?

'Does not choose Main or produce media' gives implicit exclusions, and 'exact file revision and native home access' hints at preconditions (an exact revision and native workspace). However, no alternative tool is named and there is no explicit when-to-use statement guiding the agent between this tool and its near-identical siblings.

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