search_skills

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

Annotations already declare readOnlyHint=true, openWorldHint=true, and idempotentHint=true, so the safety profile is clear. The description adds behavioral context by explaining that it returns a full index when given an empty string and specific skills when given a slug, and it notes that skills contain exact dimensions, metrics, filters, and interpretation logic. This goes beyond the annotations by clarifying the tool's output behavior and its role in the workflow.

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 well-structured and front-loaded: it starts with the purpose, then explains usage, lists available skills, and provides examples. Every sentence adds value, and the usage examples are concise and clear. It is appropriately sized for the tool's complexity.

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?

Given the tool's simplicity (one parameter, no nested objects) and the presence of an output schema, the description is complete. It covers the purpose, usage, available skills, and examples. The output schema likely describes the return structure, so the description doesn't need to explain return values. The description fully equips the agent to use the tool 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?

The schema has only one parameter 'query' with no description, and schema description coverage is 0%. The description compensates by explaining that the query is a skill name (exact slug) or an empty string to browse the full index, and provides usage examples. This adds significant meaning beyond the bare schema, though it could be slightly more explicit about the exact format (e.g., case sensitivity).

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 tool fetches analytical recipes and how-to guides from the GA4 skills library, with a specific verb ('Fetch') and resource ('GA4 skills library'). It distinguishes itself from siblings by explicitly instructing to call it BEFORE get_ga4_data for domain-specific analysis, and lists available skills, making its purpose 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?

The description provides explicit usage guidance: it says to call this tool before querying get_ga4_data for any domain-specific analysis, and gives concrete examples of how to use it (empty string for full index, exact slug for specific skill). It also lists all available skills, which helps the agent decide when to use it. This is strong guidance that differentiates it from alternatives.

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