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

Adds real behavior beyond the annotations: it discloses partial-update semantics ('only the fields given change') and the contact resolution logic (matched by email/phone, or created). Annotations already cover the write/destructive/idempotent profile, so this is a solid additive contribution.

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 sentences, front-loaded with the create/edit mode and immediately followed by contact handling and the sibling alternative. No 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?

For a 13-param write tool with no output schema, it covers the create/edit modes, the contact path, and the sibling alternative. It stops short of describing validation/defaults (e.g. new-deal stage default), which the schema partially covers.

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 54%, so it needs to pull weight; the description explains how contact_name/contact_email/contact_phone/company interact to match-or-create a contact, which the schema does not state. It leaves the remaining params (stage, value, source, status, lost_reason) mostly to the schema.

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 (add/edit) and resource (deal/opportunity) and explicitly distinguishes the upsert behavior via opportunity_id. It also names the sibling it is NOT, crm_move_opportunity, so an agent can route without opening schemas.

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 clear conditional guidance: create when opportunity_id is absent, edit when present, and route to crm_move_opportunity for pure moves or won/lost marking. No exclusion guidance for other CRM siblings (e.g. pipelines), but the core when-to-use is explicit.

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