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

With no annotations provided, the description carries the full burden and does so well: it declares 'Read-only, no side-effects, no cost' and explains the cross-key visibility semantics of the balance. It stops short of describing the return shape (currency unit, formatting) or rate/refresh behavior.

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 compact sentence with the resource front-loaded, followed by the two facts an agent actually needs (ownership semantics, safety profile). Nothing is redundant with structured fields.

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 no-parameter, no-output-schema read tool, this is sufficient: the agent knows what value comes back, whose it is, and that calling it is free and safe. The only gap is the unmentioned get_balance_full alternative, which is a routing concern rather than a completeness one.

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 tool takes zero parameters, so there is nothing for the description to disambiguate. Baseline 4 applies; no parameter claims are made or needed.

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 and resource ('Get the current shared credit balance of the workspace') and clarifies whose credits these are. It does not, however, distinguish itself from the nearby get_balance_full sibling, which an agent could easily confuse with this one.

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: the note that credits belong to the workspace owner and that member keys see the same number tells an agent what the number means, but there is no explicit guidance on when to call this versus get_balance_full, get_credit_transactions, or get_subscription.

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