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

Annotations only declare the mutation safety profile (readOnlyHint=false, non-idempotent, non-destructive). The description adds genuine behavior beyond that: partial-update semantics ('Omitted fields stay') and null-as-clear semantics. It omits permission/auth requirements and the meaning of the guard/confirm flow.

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 tight clauses, no filler, with the mutation scope front-loaded before the clearing semantics and the sibling hand-off. Every sentence earns its place.

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 6-param mutation tool with no output schema, it covers the important unknowns: partial update, clearing, and where stage changes go. Minor gaps remain around the confirm guard and what the call returns.

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 83%, so the schema does most of the work, but the description adds meaningful semantics the schema lacks: that value_cents and follow_up_at are cleared with null while other fields persist. It doesn't explain the confirm parameter or deal_type enum choices.

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 ('Set') plus the exact resource fields it mutates (value, type, notes, follow-up date) and explicitly routes stage changes to move_deal_stage, so the agent can separate it from that sibling without opening a schema.

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 conditions: omitted fields are preserved, null clears value/follow-up date, and stage moves belong to move_deal_stage. It does not spell out when to prefer this over create_deal, but the alternative routing is explicit.

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