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

With no annotations, the description carries the full disclosure burden and does well: it reveals that the result covers per-message-kind next-send times with reasons, and it surfaces the non-obvious domain rule that every message kind counts toward one shared daily limit. It does not explicitly state that the tool is read-only or what the response shape looks like, which keeps it short of a 5.

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?

Two tight sentences with the capability front-loaded and the limit semantics appended as supporting detail. Nothing is redundant, though the phrasing is slightly indirect ('whether a connection can send right now' rather than naming the result).

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 one-parameter read query with no output schema, the description adequately previews what comes back: eligibility, per-kind next-send timing with reasons, and daily-limit consumption. What is missing is the read-only confirmation and any note about scope defaults when connection_id is omitted, but the essentials are covered.

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 coverage is 100% and the single connection_id parameter is fully documented, including the fallback to an account number. The description only echoes the account framing ('the account's daily limit') without adding lookup or resolution detail, so the schema does the real work and the baseline 3 applies.

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?

The description states a specific resource and question: whether a connection can send now, and if not, when each message kind can next go out plus today's sends against the daily limit. That distinguishes it from send_message (an actual send) and from generic status tools. It earns a 4 rather than a 5 because it never names the sibling it contrasts with, leaving the agent to infer that this is the pre-send check rather than a status report.

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: an agent can infer this is the call to make before attempting send_message, but the description never says so, never states prerequisites, and never distinguishes it from connection_status or message_status. The when-to-use context exists but requires inference.

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