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

The description adds significant behavioral context beyond the annotations: the clip is SILENT, not yet in the video, representative frames from the actual downloaded rendition are attached, and handles survive later turns and MCP worker processes. It does not contradict the annotations (readOnlyHint=false, destructiveHint=false, etc.), and actually reinforces them by describing a non-destructive, additive operation.

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 description is moderately long but each sentence contributes essential information. It front-loads the project-scoped warning and uses clear directives (DOWNLOAD, place it, inspect, tell the user). It could be slightly more compact, but the structure is logical and easy to scan.

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?

With no output schema, the description gives a hint of the result ('returns the project identity with its result') and mentions attached frames. It covers all critical call requirements: id matching, project_id sourcing, placement guidance, and user notification. Minor details like error handling are absent but not essential for correct invocation.

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?

Despite the schema having only 50% coverage (id lacks description), the description thoroughly explains both parameters: id must exactly match a project result and handles persist, while project_id is a required immutable scope copied from project state, not guessed from the active pointer. This compensates fully for the schema's gaps.

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 clearly states the action: 'DOWNLOAD one saved search_stock or research_broll result and save it as a project asset.' It specifies the resource (stock media) and the verb (add), and distinguishes itself from other add_* tools by focusing on downloading and saving stock media. The project-scoped warning further clarifies its specific scope.

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 description explicitly states when to use this tool and how to use it correctly: it is project-scoped, requires an exact id match, and provides placement guidance by naming alternatives like add_overlay(fit='cover') and insert_media. It also advises inspecting frames before placement, giving clear conditional usage instructions.

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