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

Annotations already declare write/destructive/idempotent/open-world, but the description adds traits the annotations cannot convey: partial-update semantics ('Only the fields you pass change'), that it 'overwrites the previous values of those fields' (what gets destroyed), that it 'Sends no notifications', and the underlying endpoint POST /leads/{lead_id}. This is meaningful side-effect disclosure rather than restatement.

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 the 'WRITE:' marker, then field scope, then constraints and endpoint in a tight sequence. Slightly dense with the colon-delimited field list, but every clause carries operational information and none is 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 7-parameter write tool with nested objects and no output schema, the description covers mutation semantics, required-input constraint, notification behavior and endpoint. Minor omissions remain: no mention of what the response contains or failure/permission behavior, though annotations carry the safety profile.

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; however the description adds a real constraint not present in the schema — the schema marks only lead_id as required, while the description states 'At least one field is required' among the updatable set. The field enumeration also confirms intent of custom_fields vs additional_fields.

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 ('WRITE: update a lead's sales data in WhatConverts') and enumerates the exact updatable fields (quotable, quote_value, sales_value, lead_url, custom/additional fields). This cleanly separates it from whatconverts_create_lead, whatconverts_get_lead and whatconverts_list_leads without needing to open 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 clear operative conditions: 'At least one field is required' and 'Only the fields you pass change', which tells the agent how to call it. It does not explicitly name alternatives or state when-not to use it (e.g. vs create_lead or a bulk update), so it stops short of full routing guidance.

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