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

Annotations already declare readOnlyHint=false, destructiveHint=false, idempotentHint=false and openWorldHint=false, so the safety profile is covered. The description adds one behavioral fact — that unknown custom field codes are rejected — but that same warning is already repeated almost verbatim inside the custom_fields schema entry, so the incremental value is modest.

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 short sentences with the action front-loaded and the prerequisite second; there is no padding. Minor redundancy exists because the crm-schema instruction duplicates the schema's own warning, costing a perfect score.

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?

An output schema exists, so return values need no explanation, and the required title parameter is obvious. Still, for a five-parameter create tool with nested custom_fields and overlapping entity-linking capability, the description omits the create-vs-attach-vs-update decision, which is the main thing an agent could get wrong.

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 100%, including detailed guidance on custom_fields, so the baseline is 3. The description contributes nothing parameter-specific beyond echoing the schema's crm-schema instruction, and says nothing about how the three ID-array parameters interact with the dedicated attach tool.

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?

The description gives a specific verb and resource ("Create a new note") scoped to the CRM, so the agent knows exactly what object is produced. It does not differentiate itself from siblings like update-note-tool or attach-note-to-entities-tool, leaving the boundary implicit.

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?

It supplies one concrete prerequisite (read crm-schema before supplying custom fields), which is real guidance. However, it never states when to use this tool versus attach-note-to-entities-tool for linking people/companies/opportunities, nor how it relates to update-note-tool, so the main selection ambiguity is unresolved.

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