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

Annotations already declare readOnlyHint=false, destructiveHint=false, openWorldHint=false, so the agent knows this is a contained, non-destructive write. The description adds meaningful context beyond that: modules live at organization level and are shared across projects, and deletion is unsupported. It does not say what happens if the name collides or if parent_folder_id is invalid, but the added context is solid.

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?

Three compact sentences, front-loaded with the create action and the tree-choice branching, followed by nesting and the deletion caveat. No filler and no restatement of the title.

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, the description covers the branching modes, the required nesting rules, and an important negative capability (no delete). It stops short of explaining return behavior or failure modes for invalid parent/project ids, which is a minor gap given the clean schema.

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 coverage is 100%, so the baseline is 3, but the description adds real semantics: which tree the default applies to, that project_id is inapplicable for modules, and that omitting parent_folder_id means top level. That is useful reinforcement and clarification rather than pure duplication.

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 (Create) plus resource (folder) and immediately enumerates the three distinct trees it can operate on, with the default called out. This differentiates it cleanly from siblings like tm_list_folders, tm_update_folder, and tm_create_project.

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?

Explicitly states the conditions that select each mode: pass project_id for Test Cases/Test Runs trees, omit it for organization-level Modules, and optionally nest via parent_folder_id. It also sets a boundary by noting that deletion is not available through this connection, which steers the agent away from expecting a delete/undo path.

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