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

Goes well beyond the annotations (readOnlyHint=false, openWorldHint=true, destructiveHint=false) by disclosing that exactly one message goes to the passed leads, that links are allowed, that a colleague can be CC'd, that Crexi publishes no recipient limit, that confirmation is on by default, and that a Cotlet API key with app access is required. For an outbound-message tool this is unusually complete disclosure.

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?

Roughly six short sentences, with the core action, the Pro restriction and the confirmation requirement front-loaded so an agent gets the key constraints immediately. Minor redundancy between the 'Sends one message...' sentence and the opening line, but no wasted filler.

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?

No output schema exists, so the description carries the return-behavior burden, and it does state that it sends one message per invocation. With annotations present and prerequisites, confirmation policy and side effects all covered, an agent has enough to invoke correctly; the only soft spot is that it never says what a successful response contains.

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%, so the schema already documents lead_ids, subject, body and cc. The description restates the subject/body/cc semantics and adds one useful detail (links are permitted in the body), but nothing that meaningfully exceeds the schema. 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?

States a specific verb and resource ('Email one lead or a group of leads from Crexi'), plus the scope (single vs. group) and that the message comes from the user's own Crexi account. This clearly separates it from read-oriented siblings like crexi_list_leads, crexi_get_lead and crexi_export_lead_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?

Gives real usage context: 'Pro only', that lead IDs come from list_leads, that per-call confirmation is on by default but can be switched off, and that the user must be asked before each call because it reaches other people. It does not explicitly compare itself to a named alternative messaging tool, so it stops just short of a 5.

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