add_weighted_value_keyframe

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

Annotations declare readOnlyHint=false, idempotentHint=false, destructiveHint=false, and the description's 'Write a single key' is consistent with a non-read write. It adds the 'first section' scoping and reports save/save_error in the return payload, but does not state permissions, reversibility, or what happens on repeat calls.

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 behavioral sentence is tightly front-loaded and wastes no words. The inline Returns block is somewhat long but earns its place since no output schema exists to convey the response shape.

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 mutation tool with no output schema, documenting the return object (key_index, key_count, saved, save_error) compensates well for the missing output schema. The main remaining gap is prerequisites/error conditions around the 'existing track' requirement.

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, including defaults and interp modes. The description adds no parameter semantics beyond what the structured schema provides, so the baseline of 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+resource: writing a single key onto an existing float property track's first section, plus the interp modes. An agent can distinguish this from add_weighted_value_track (which creates the track) without opening the schema. It stops short of explicitly naming sibling tools.

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?

The word 'existing' implies the track must already be present (use add_weighted_value_track first), which is useful but only implicit. There is no explicit when-to-use vs when-not statement or named alternative among the many sibling sequence/keyframe tools.

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