List Accounts

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

Annotations already cover the safety profile (readOnly, idempotent, non-destructive, closed-world), so the bar is lower; the description adds the non-obvious exclusion rule that user-hidden accounts are omitted and points to getAccountAccess. It does not discuss ordering or whether the result set is ever empty, but the substantive behavioral facts are present.

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?

A single front-loaded sentence with the key scoping constraint first. It is dense with nested parentheticals — 'identities (id, email, name, isDefault: the from of compose tools)' requires re-reading — but nothing is redundant.

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 and no parameters, the description carries the return-shape burden and does so by listing each field and its cross-tool meaning. What remains unstated (ordering, count limits) is minor for an account-list tool.

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?

Zero parameters, so the baseline is 4. The description instead spends its words on return-value semantics (accountId linkage, isDefault as the compose 'from'), which is the correct use of space for a no-arg tool.

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?

States a specific verb (list) and resource (accounts), and immediately scopes it: accounts the MCP client may use. It also enumerates the returned fields (id, name, type, identities), so an agent knows exactly what it gets back and can distinguish this from getAccountAccess.

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?

Implied usage is clear — this is the entry point for discovering account IDs before calling other tools, and the description ties `id` to 'the accountId of other tools'. The parenthetical reference to getAccountAccess signals where to go for hidden accounts, but the when/when-not routing is implicit rather than spelled out.

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