sw_list_friends

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

Annotations already declare readOnlyHint=true, so the safe read nature is covered. The description adds useful behavioral context beyond that: the default 'compact' response shape, the joined name field, and the difference between compact and full views. It doesn't cover pagination or error behavior, but for this simple read-only list tool the disclosure is solid.

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 two sentences with no filler. The core function is front-loaded, the use case follows, and the compact/full distinction is explained in an organized way. Every sentence contributes information the agent needs.

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 list tool with one optional parameter, the description covers the operation, the use case, the default behavior, and the output shape for both views. Since there is no output schema, describing the returned fields is especially important, and this description does it well. The read-only annotation covers safety, so nothing essential is missing for correct invocation.

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?

Though the schema already describes the 'view' parameter well (100% coverage), the description adds concrete value: it explains the default value ('compact'), what the compact response contains (id, name, email, registration_status, balance), and that 'full' returns Splitwise's raw records with separate first_name and last_name. This goes beyond the schema by tying semantics to real output 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?

The description opens with a specific verb and resource: 'List all Splitwise friends.' It clearly differentiates this tool from sibling tools like sw_create_friend and sw_delete_friend, and the use case—resolving a name to a user_id—adds further clarity. No ambiguity remains about what the tool does.

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 explicitly states when to use the tool: 'Use this to resolve a friend's name to a user_id before adding them to a group or building a custom expense split.' It gives clear context and downstream actions, though it doesn't explicitly mention when not to use it or name alternative tools. This is still strong practical guidance.

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