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

Annotations already declare readOnlyHint=true, idempotentHint=true, and destructiveHint=false, so the safety profile is covered. The description adds context about the specific agents and the benefit of session-wide persistence, but does not add new behavioral details beyond confirming it is an explanation. This is consistent with annotations and adds modest value.

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?

A single sentence, front-loaded with the verb 'Explains' and the object. Every phrase earns its place: the agent list and the session-vs-message contrast are directly useful. No filler or redundancy.

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 simple instructional tool with one parameter, no output schema, and annotations that already convey idempotency and read-only behavior, the description is fully adequate. An agent can understand what it does, who it applies to, and why it matters without needing more information.

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?

The schema doc for the 'tool' parameter is complete (100% coverage) and already enlists the five possible values. The description repeats that same list without adding further detail on syntax, defaults, or usage, so it does not go beyond the schema. Per the rubric, baseline 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?

The description uses the verb 'Explains' and names the exact resource ('where a DESIGN.md belongs for a given coding agent'), with a specific list of agents (Claude Code, Cursor, v0, Codex, Lovable). It clearly differentiates itself from sibling tools like get_design_md or get_agent_rules by focusing on placement/installation rather than retrieval.

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 clearly communicates its purpose and scope (which agents it covers and the outcome of applying design rules across sessions), which gives strong context for when to use it. However, it does not explicitly name alternative tools or state when not to use it, so it falls short of a 5 but is clear enough.

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