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

Goes beyond the annotations by disclosing the cost model ('$0.05 per call; nothing if it fails'), the fact the email is sent in the business's name, and that the booking appears in the applicant's history. Annotations cover the safety profile; the description adds real operational context, though it doesn't address duplicate-invite or failure handling.

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 dense sentences that front-load the core action and follow with side effects and cost. No filler, though the parenthetical '(calendar area)' is slightly cryptic.

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 mutation/email tool with no output schema, the description covers the key side effects, cost, and optional stage move well. It stops short of describing error conditions or what the tool returns, but overall an agent has enough to call it correctly.

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 50% (message and meeting_type documented, applicant_id and move_to not). The description compensates for move_to by explaining it moves the applicant 'to a stage such as Interview,' giving semantic meaning the schema lacks, but applicant_id remains undocumented. Baseline 3 fits.

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 an applicant a link to book an interview on one of your calendar's meeting types.' This clearly distinguishes it from siblings like hiring_email_applicant (plain email), calendar_book (direct booking), and hiring_move_applicant (stage move).

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 description implies the scenario (invite an applicant to self-book an interview) and notes the optional stage move, but it never explicitly names alternatives such as hiring_email_applicant or hiring_send_assessment, nor states when-not to use this tool. Usage is inferable but not routed.

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