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

Annotations already declare readOnlyHint, idempotentHint, and openWorldHint=false, so the safety profile is covered. The description earns credit for adding behavioral context beyond that: it discloses the content mix returned (editorial picks plus most recent public user-created lists), which tells the agent what data to expect. It stops short of describing ordering or pagination behavior.

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?

Two tight sentences with zero filler. The resource definition and example are front-loaded, followed by the routing pointer to get_runlist, which is the natural reading order.

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 read-only browse tool with no output schema, the description covers what is returned and where to go next, which is most of what an agent needs. The remaining gap is the limit parameter, whose range and defaulting behavior (max 20, default 10) are only inferable from the 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 description coverage is 0%, so the description carries the burden for both parameters. It implicitly explains the 'kind' selection by saying results include editorial picks and recent user lists, which maps to featured/recent/both, but it says nothing about the 'limit' parameter's effect, cap, or default behavior.

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?

Uses a specific verb ('Browse') plus a named resource ('Skamper run lists') and clarifies what the resource is with a concrete example ('Best UK trail half-marathons'). It also explicitly separates this tool from the sibling get_runlist, which drills into a single list, so an agent can pick between them without opening a schema.

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 clear when-to-use context (browsing curated collections and recent public lists) and names the follow-up alternative, get_runlist, for inspecting routes inside a list. It does not state any exclusion or when-not condition, so it stops just short of full routing guidance.

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