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

Annotations already declare a non-read-only, idempotent, destructive mutation, so the safety profile is covered. The description adds a genuine behavioral constraint not present in the annotations or schema: the email field is only mutable before first contact. It does not explain what 'destructive' means for field overwrites, but the annotation carries that.

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, zero waste, and the core action is front-loaded ahead of the constraint. Nothing could be trimmed without losing information.

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 15-parameter destructive mutation with nested objects and no output schema, the description is thin. It omits whether omitted fields are left unchanged, how customFieldTypes/customFieldLabels interact with customFields, and any permission requirements, though annotations and the partial schema cover some ground.

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 only 47%, so the description must compensate. It names the parameter categories (fields, tags, custom fields, status, email) and flags the email precondition, which maps to several of the 15 parameters, but adds no format or syntax detail for the many undocumented scalar fields (website, jobTitle, location, etc.).

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 ('Change a lead's fields, tags, custom fields or status') and enumerates the updatable categories. The singular 'a lead' implicitly separates it from the bulk_* siblings, though no sibling is named explicitly.

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?

The precondition 'The email can only change before the lead is first contacted' is usage-relevant, but there is no explicit guidance on when to prefer this over bulk_set_lead_status, bulk_add_lead_tags, or update_campaign. Usage is implied rather than stated.

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