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

Annotations already declare it a non-read-only, destructive, idempotent write, so the bar is lower. The description still adds real behavior beyond that: partial-update merge semantics, the side effect that closing via probability triggers won/lost status, and the non-obvious note that no email is sent to a new owner.

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 a 'WRITE:' risk marker, then a tight sequence of clauses with no filler. Every sentence carries an operational rule; the trailing 'PUT /deals/{id}' is useful endpoint context.

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 20-parameter mutation tool with a nested custom_fields object and no output schema, the description covers the highest-risk behaviors well. It omits how arrays (tag_ids, person_ids) replace rather than append, though the schema itself documents that.

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 100%, so the baseline is 3. The description adds cross-field semantics the schema doesn't carry — that won/loss reason ids should accompany a probability-driven close — and re-emphasizes stage_id and archived usage, going modestly beyond the per-parameter docs.

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?

Opens with 'WRITE: change fields of a deal' — specific verb plus resource — and immediately scopes it as a partial update ('only the fields you pass change'). This cleanly separates it from pipelinecrm_create_deal and the read-only pipelinecrm_get_deal siblings.

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 explicit conditional guidance for the non-obvious cases: use stage_id to move stage, set probability to 100/0 to close won/lost (and supply reason ids), and archived: true to archive. It does not, however, name an alternative sibling or state when not to use this tool.

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