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

Annotations already declare readOnly, idempotent, openWorld and non-destructive, so the safety profile is covered. The description adds genuinely non-obvious behavior beyond that: 'Counts as browsing' signals a consumption/quota side effect, and 'null where the account has no such plan' defines the absent-value contract.

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?

Three short sentences, front-loaded with the applicability constraint, with no filler or repetition of the title. Slightly telegraphic phrasing ('Counts as browsing') costs a little clarity but not length.

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 does useful work by enumerating the plan keys and the null case. However, it omits what happens for a non-LinkedIn account (error vs null) and says nothing about account_id, leaving real gaps for a read tool with an openWorld hint.

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 0% and the description never mentions account_id, so the single parameter's meaning comes entirely from the schema (uuid format, required). The parameter is largely self-explanatory, but per the low-coverage rule the description should have compensated and does not.

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?

Names the resource precisely ('InMail credits on this account') and scopes it to LinkedIn accounts, so an agent can predict the return shape by plan. It stops short of naming a sibling such as get_account_limits, so the boundary with adjacent limit/health tools must be inferred.

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?

The one usage-relevant rule given is the applicability gate 'LinkedIn accounts only', which tells the agent when the tool does not apply. There is no explicit when-to-use versus alternatives guidance (e.g. versus get_account_limits or get_messaging_usage), leaving selection implied by the resource name alone.

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