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

Adds substantial context beyond the hints: 'No media generation, credit charge or library change' discloses the side-effect boundary, 'Returns a new brief and quote' discloses the return shape, and the revision/recipe_key instructions disclose concurrency and chaining requirements. With annotations only giving generic hints, this carries the design well, though what a 'replace' discards is not spelled out.

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?

Front-loaded with the operation, then preconditions, then side-effect profile and chaining. Six short sentences with essentially no waste; 'Photo format is shared across the shoot' is the only line whose relevance is slightly opaque.

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 7-parameter planning mutation with no output schema, the definition covers what changes, what is returned, what is not touched, and the required edit protocol. Only the indexing params (shot_index) are left implicit, which is minor.

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 57%, so some params already carry documentation. The description reinforces expected_brief_revision and the append-vs-replace meaning of step_index, but adds little on shot_index, brief_id, or board_id, and much of what it says (default looks, omit to append) is already in the schema.

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 concrete verb pair (append or replace) and a concrete resource (one background removal) that clearly sets it apart from the other plan_shoot_* siblings. The scope (selected looks via a named flow) is also specified, so the agent knows exactly what is being modified.

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?

Gives clear preconditions and sequencing: 'requires the current brief revision' and 'Read the returned recipe_key before the next edit.' The default-looks behavior is stated. It stops short of naming any alternative tool (e.g. plan_shoot_edit or plan_shoot_image) or saying when not to use it, but the usage context is otherwise clear.

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