add_montage_section

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

Annotations only say this is a non-readOnly, non-idempotent, non-destructive write. The description goes well beyond that: it discloses the undo transaction wrapper, the exact success payload fields, the no-op case (same name at same start time yields changed=false/saved=false with no modification or save), and the failure shape (success=false, saved=false, save_error). That is unusually complete behavioral disclosure.

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?

The capability and the sibling routing are front-loaded in the first sentence, and the remaining sentences each carry distinct behavioral facts (return fields, no-op case, failure case). It is dense and slightly long, but no sentence is filler, and the trailing Returns line compensates for the absent output 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?

There is no output schema, but the description enumerates the returned keys and explains the meanings of the non-obvious ones (added, changed, saved, save_error), plus the no-op and failure semantics. Combined with full schema coverage and annotations, an agent has everything needed to call and interpret this tool.

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 coverage is 100%, so the baseline is 3. The description adds meaning beyond the schema by clarifying that section_name doubles as a lookup key (matching an existing section triggers a move rather than a duplicate) and that start_time is interpreted as an absolute time. That semantic is not inferable from the field descriptions alone.

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 gives a precise verb+resource ("Add a composite section to a UAnimMontage") and adds the upsert nuance ("or move the existing section of that name there"), so an agent knows this both creates and relocates sections. It explicitly distinguishes itself from link_montage_sections, which is the nearest overlapping sibling.

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 names an explicit alternative and the condition that selects it ("it does not link sections (use link_montage_sections)"), which is strong when/when-not routing. It does not address the overlap with set_montage_section_start_time, which also changes a section's start time, so the guidance is clear but not fully exhaustive.

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