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

Annotations already declare readOnlyHint=true, destructiveHint=false, and openWorldHint=false, so the safety profile is covered by structured data. The description adds useful framing about what a segment is and how segment_id is consumed downstream, but says nothing about scope (per-site), ordering, or pagination.

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?

One sentence, front-loaded with the resource and free of filler. It is efficient, though it spends its words on defining the concept rather than stating the operation, which is a small structural miss.

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?

A simple one-parameter read tool whose annotations cover safety, so requirements are low. However, with no output schema, the description should ideally say it returns a list of segments (with their ids) for the given site — that return expectation is left implicit.

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% and the single site_id parameter is documented as 'Site id from list_sites', so the schema carries the load. The description never mentions site_id or the per-site scoping of results, adding nothing beyond the schema — baseline 3.

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?

Names the specific resource (saved segments) and defines what it is with concrete examples ('Paid traffic', 'Mobile in Germany'), which lets an agent distinguish it from sibling lists like list_goals or list_sites. It never states the action verb explicitly (that it returns the collection), but the resource is 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 clause 'can be applied to any report with segment_id' explains downstream usage of segments rather than when to call this tool versus alternatives. No condition, prerequisite, or sibling tool is named, so the agent gets no routing guidance.

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