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

Annotations already declare readOnly/idempotent/non-destructive/closed-world, so safety is covered. The description adds genuine behavior beyond that: the return format (Markdown with code examples), included prompts and metadata, related-rules enrichment, and the failure fallback ('returns suggestions for similar rules'). It stops short of describing the error surface in more detail, but the added context is substantive.

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 core action, then bolded workflow and related-rules sections that are scannable. It is somewhat long for a simple getter, but each block (usage, workflow, related) carries recoverable information rather than filler.

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?

Output schema exists, so return-value details are a bonus rather than a requirement, yet the description still summarizes content and prompts. Combined with the workflow guidance and fallback behavior, an agent has everything needed to call this tool correctly in context.

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% and both parameters (slug, includeUrl) are documented in the schema itself, so baseline is 3. The description adds a small amount via the missing-slug behavior but doesn't clarify slug format or the effect of includeUrl beyond what the schema already says.

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?

Specific verb and resource ('Retrieves a single frontend development rule by its unique slug') with clear scope. It also names its siblings (search_rules, check_rule, fix_rule, explain_rule) so an agent can distinguish this lookup tool from validator/fixer tools without opening their schemas.

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 when to use it ('Use PROACTIVELY when reviewing or debugging frontend code') and where it fits in the workflow (after review_code or search_rules). It also points to the natural follow-up tools and their conditions, leaving little to inference.

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