add_subtitle_cue

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

Annotations declare the safety profile (not read-only, not destructive), so the bar is lower, yet the description adds real behavior: dedup by FSubtitleAssetData::operator== over text/duration/start_offset/priority/subtitle_type, and the already_existed:true return path. It does not state permission/editor requirements or confirm what 'saved' implies, leaving a small 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?

The operation verb is front-loaded and the two-part structure (behavior then returns) is tight with no filler. The 'Returns' block is genuinely useful rather than redundant because no output schema exists, though the dense internal type/operator names cost a little readability.

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 an 8-parameter mutation with no output schema, the description covers both the operation and the exact return shape, which is what an agent most needs. It does not address permissions or use-case context, but the core call semantics are complete.

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 all 8 parameters and their defaults/enum values. The description restates the field groups (text/timing/priority/type/comment) but adds no syntax or format meaning beyond the schema, 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 and resource: 'Appends a subtitle cue ... to a USubtitleAssetUserData,' and identifies the built-from fields. An agent can tell it is an additive mutation. However, it never names or contrasts against siblings like set_subtitle_cue_text, set_subtitle_cue_timing, or create_subtitles_asset, so sibling differentiation is missing.

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?

There is no explicit when-to-use, when-not-to-use, or alternative routing. The dedup note implies you can re-add the same cue safely, but the description never tells the agent when this tool is the right choice over set_subtitle_cue_text/timing or when a cue should be updated instead of added.

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