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

Annotations already provide readOnlyHint, openWorldHint, idempotentHint, and destructiveHint, lowering the bar. The description adds value by mentioning 'bounded' results (hinting pagination) and listing the returned fields, giving agents a fuller picture of the tool's behavior beyond the annotations.

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 sentences with no wasted words. The core action and field list are front-loaded, followed immediately by the distinct purpose. Every sentence adds useful information and the description is appropriately sized for a straightforward list tool.

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?

With no output schema, the description compensates by listing the returned fields, which is helpful. The pagination parameters are already in the schema, and annotations cover safety. It omits explicit discussion of cursor usage, but 'bounded' hints at it. Overall, the description covers what an agent needs to invoke the tool correctly, with minor gaps around output shape specifics.

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%, so all three parameters (limit, cursor, _apiKey) are fully documented in the schema. The description contributes no additional parameter-level meaning beyond the word 'bounded', which indirectly relates to limit and cursor. Baseline 3 is appropriate.

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 begins with an active verb and specific resource: 'Return bounded Segment sources' and enumerates the exact fields returned (IDs, names, slugs, enabled state, metadata, labels, settings). It also adds a distinct purpose ('Answers which applications and systems send customer events into the workspace'), which clearly separates it from sibling tools like segment_list_destinations or segment_list_warehouses.

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 implies usage by stating it answers which apps/systems send events, giving an agent context to select it for source discovery. However, it never explicitly names alternatives, exclusions, or 'when not to use' cases, so the guidance remains implicit rather than direct.

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