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

Annotations already declare readOnlyHint, idempotentHint, and destructiveHint=false, so the description's job is narrower. It still adds real value with 'Free' (no credit consumption) and by surfacing 'whether this key is read-only', which tells the agent it can self-inspect credential scope before attempting writes.

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?

One sentence with zero filler: verb first, then a tight list of returned fields, with the cost note ('Free') as a short trailing clause. Everything after 'Show this account' earns its place.

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?

No parameters, a full output schema, and annotations covering the safety profile mean the description only needs to frame intent and cost. It does both; the only gap is not stating the relationship to check_company or when an agent should prefer each.

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; there is nothing for the description to disambiguate. 'this account' / 'this key' usefully clarifies that the target is implicit from authentication rather than a parameter.

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?

A specific verb ('Show') plus the resource ('this account'), followed by an enumeration of exactly what is returned: credits available, credits held by in-progress briefs, applicable limits, and key read-only status. That enumeration also separates it in spirit from siblings like check_company and list_briefs, though it never names an alternative explicitly.

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: 'this account' and 'this key' signal it is about the caller's own credential rather than another entity. There is no explicit when-to-use, when-not-to-use, or pointer to check_company for company-level data.

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