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

Annotations already declare readOnlyHint, idempotentHint, destructiveHint=false, and openWorldHint=false, so the safety profile is covered. The description adds genuinely new context: the read/write scope semantics, the rule that production is not charged to the wallet when the user operates the platform, and the '$0' cost signal, none of which appear in 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?

Front-loaded with the core answer ('The principal behind this credential') followed by a scoped list of returned fields and the cost. The single sprawling sentence with stacked parentheticals is dense and slightly hard to parse, but with no output schema every clause carries real information, so little is wasted.

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 must carry the return-value burden, and it does so field by field. Remaining gaps are minor: no statement of what happens when the credential is invalid or absent, and no indication of format for the wallet balance beyond the USD unit.

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 schema declares zero properties, so there are no parameters to document and the baseline is 4. The description correctly adds no parameter discussion and instead spends its budget on the return payload.

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?

Opening clause 'The principal behind this credential' states precisely what the tool returns, and the enumeration of fields (credential kind/scopes, organization, user, wallet balance, legal, server version) leaves no ambiguity. It is trivially distinguishable from all siblings, which are project/script operations, though the distinction comes from subject matter rather than explicit differentiation.

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?

There is no explicit 'use this when...' statement and no named alternatives, but usage is strongly implied by the content: an agent reading 'credential kind and scopes', 'wallet balance', and 'legal' infers this is the self-inspection tool for auth, billing, and legal acceptance state. The '$0' suffix hints it is cheap to call freely, which is a mild usage cue.

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