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

Annotations already declare readOnlyHint=false, openWorldHint=true, idempotentHint=false and destructiveHint=false, so the mutation/safety profile is covered. The description adds genuine behavior beyond that: an email reply SLA ('within one business day') and a validation rule that temporary inboxes are refused, plus a consent requirement. It does not address duplicate submissions, but with annotations carrying that load a 4 is warranted.

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?

Front-loaded with purpose, then usage conditions, then a compact parameter glossary; every line carries information. The indented parameter list is slightly redundant in presentation but each entry earns its place, so no real waste.

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 side-effecting, five-parameter, no-output-schema tool, the description covers purpose, consent preconditions, validation behavior and expected turnaround, which is most of what an agent needs. Only minor gaps remain, such as whether repeated calls create duplicate messages, and the annotations already imply the non-idempotent nature.

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%, so the description carries the full burden, and it does: each of the five parameters is glossed with meaning (prospect_email required with the temp-inbox caveat, project_brief = 'the message', requested_window optional = when they want to hear back). This fully compensates for the bare schema titles.

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 ('Send a message to TESSA's sales team') and grounds it in a concrete analogue ('the same as the contact form on tessa.tech'). This clearly separates it from siblings like request_strategy_session (booking a call) and get_contact_info (retrieving details).

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 an explicit selection rule: 'Use this when the user wants TESSA to contact them but does not want to book a call', which explicitly routes against the booking sibling. It also adds a hard precondition ('Only call it when the user has asked to and has given their real email'), leaving nothing to inference.

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