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

Annotations already declare readOnlyHint=true and destructiveHint=false, so 'reads the balance only and spends nothing' is largely reinforcement. It does add genuine context beyond the annotations by specifying the auth prerequisite ('Needs the user's Cotlet API key with access to this app').

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-loads the purpose and the when-to-use rule in a short span; most sentences earn their place. The leading 'Property Finder:' label duplicates the title and the safety restatement is close to redundant with the annotations.

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-param read with no output schema, the description covers what it returns (upgrade credits), the auth requirement, and the usage trigger. Sufficient for correct invocation, though it does not describe the balance's format or any expiry/unit detail.

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 no parameters, which is the baseline-4 case; there is nothing for the description to disambiguate. It correctly adds no spurious parameter discussion.

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 ('Returns the credits available for upgrades') and frames it as 'the credit balance PF Expert shows for your agency', which an agent can distinguish from the spending sibling upgrade_listing without opening a schema.

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?

Gives an explicit when-to-use rule with its rationale ('Check it before upgrade_listing so the agent does not plan a spend you cannot cover'), naming the exact alternative tool it gates. Nothing is left to inference.

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