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

Annotations already declare readOnlyHint, idempotentHint, openWorldHint false, and non-destructive; the closing 'Reads only' is consistent with them rather than contradictory. The description adds useful behavior context beyond annotations: the placeholder-name diagnostic, plan-related send refusals, and the fact that only allowances near their limit are surfaced while usage_status holds the full list.

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 very long run-on sentence packs a dozen return fields plus several usage triggers, which makes it dense to parse. It is front-loaded with the account identity question and ends with the use cases, but splitting the field list from the when-to-use guidance would read much better.

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 return-value burden and does so by enumerating the reported fields and pointing to usage_status for the exhaustive allowance list. Coverage is strong for a zero-parameter read tool; only the exact shape of contact counts and the handle field is left implicit.

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 the baseline is 4. The description correctly implies no inputs are needed and instead spends its words on what the call returns.

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 subject (the RelayLink account this connection acts as) and enumerates exactly what it reports: name, address, placeholder status, contact counts, plan, allowance, message length limit, and server handle. It is clearly distinguishable from siblings like usage_status, set_my_name, and upgrade_plan.

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 explicit trigger conditions: who am I connected as, which RelayLink is this, why a recipient saw an odd sender name, why a send was refused for want of a plan, and how long a message may be. It also routes the agent to usage_status with 'usage_status lists them all'.

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