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

Annotations already declare readOnlyHint=false, idempotentHint=false and destructiveHint=false, so the safety profile is covered; the description adds owner scoping and the duplicate-name pre-check, which effectively explains the practical consequence of non-idempotency. It stops short of stating what happens on a name collision (error vs. silent duplicate), which would have made it a 5.

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 short sentences, front-loaded with the WRITE marker and the core action, then the guardrail, then the return shape. No filler or restated schema content.

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 two-parameter creation tool with no output schema, the description covers the action, the prerequisite check, and the return shape {id, name, …}. An agent has everything needed to decide and invoke correctly.

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 both `name` and `emoji` are already documented in the schema and the baseline is 3. The description only tangentially touches the name parameter (uniqueness check) and says nothing about the optional emoji, so it adds little beyond the structured fields.

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 and resource ("create a new feed playlist") and adds the owner-scoping constraint, which distinguishes it from add_to_playlist and remove_from_playlist. The WRITE marker and named sibling make the tool's role unambiguous.

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 explicit when-to-use and when-not-to-use guidance: call list_playlists first, only create when the name genuinely doesn't exist, or when the user confirms. It even names the failure mode (auto-creating from a typo) that the rule prevents.

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