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

Annotations already cover the safety profile (readOnlyHint, idempotentHint, destructiveHint=false), so the bar is lower. The description adds genuine behavioral context beyond that: it explains that the MCP connector and REST API v1 are one platform entitlement and states what happens to API and MCP access when a free trial ends.

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?

The purpose is front-loaded, but the second half is a long run-on sentence with repeated framing ('one account, one key, one Pro entitlement') that reads as promotional rather than informational. It earns its place only partially.

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 carries the burden of conveying return content, and it does so thoroughly, including entitlement/trial-end behavior. Nothing critical for correct invocation appears missing, though it never ties the key_prefix parameter to the filtering behavior.

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?

Schema description coverage is 100% and the single optional key_prefix is fully documented in the schema, so the baseline is 3. The description never mentions key_prefix or the scoping behavior of focusing on one key, adding nothing over the schema.

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 ('The state of the FirmLedger REST API for this account and API key') and enumerates the payload it returns (identity, plan, scopes, budgets, usage, endpoint catalogue). However, it never names or contrasts with plausible siblings such as list_api_keys or manage_api_keys, so the agent must infer the distinction.

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 statement of when to call this versus list_api_keys or manage_api_keys, no prerequisites, and no exclusions. Usage is only implied by the description of what the payload contains.

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