l402-credentials

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

The readOnlyHint annotation already marks it safe, and the description adds genuinely useful behavior: balances are cached and possibly stale, and the lastUsed timestamp is the way to judge freshness. This is beyond the annotation and gives the agent a realistic expectation of data reliability. No contradiction exists.

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 front-load the action and displayed fields, then add the stale-balance caveat. Every sentence carries operational value, and no redundant filler is present.

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 zero-parameter, read-only listing tool, this description is complete: it says what is listed, what fields are shown, and warns about cache freshness. The lack of an output schema is mitigated by naming the visible fields, and there are no params/options whose behavior would need elaboration.

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?

The input schema is empty (0 parameters), so there are no parameter semantics for the description to enrich. With schema coverage at 100%, the description cannot add anything parameter-related, and the baseline of 4 applies.

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 the action ('List all stored L402 credentials') and the resource/scope precisely, then names the displayed fields (origin, cached credit balance, server type). This distinguishes it from siblings like l402-store-token or l402-balance by focusing on stored credentials rather than operations or current balance.

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?

Usage is only implied: an agent can infer this is for inspecting stored credentials, and the 'cached/may be stale' caveat hints that l402-balance might be the alternative for fresh numbers. However, it never explicitly states when to prefer this tool or names an alternative, so it stops short of clear routing guidance.

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