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

Annotations already declare readOnlyHint=false, destructiveHint=false and openWorldHint=false, so the safety profile is known. The description adds only that toggling is possible; it never says whether 'params' replaces the entire parameter set or is merged, whether unspecified values are preserved, or how an agent discovers valid parameter keys for the free-form object.

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 front-loaded sentence with no filler, and the two capabilities are stated before any qualifications. It is efficient, though its brevity comes at the cost of the missing context noted elsewhere.

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 5-parameter mutation tool with a nested object and no output schema, the description is under-specified: it does not cover key resolution, merge semantics, or the effect-parameter vocabulary. It tells an agent what the tool does but not enough to call it confidently with the free-form params argument.

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 only 20% (just projectId's default), and the description sheds no light on clipId vs effectId, the free-form 'params' map, or the 'enabled' boolean beyond restating it. The most semantically demanding parameter, a nested open-ended object, remains completely undefined.

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 ('Change') plus the resource ('an effect') and enumerates the two modes of change: parameter edits and on/off toggling. That distinguishes it reasonably from add_effect, remove_effect, and move_effect without naming them explicitly.

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 guidance on when to use this versus copy_effects, clear_effects, remove_effect, or move_effect, and no mention of prerequisites such as needing a loaded project or existing effect. Usage must be inferred entirely from the tool name.

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