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

Annotations already declare destructiveHint=true and idempotentHint=true, so the safety profile is covered. The description adds genuine behavioral context beyond that: a state-machine constraint on pipeline_stage transitions (no backward moves once ACTIVE/CHURNED) that is not encoded in the schema. It stops short of stating what happens to fields left unspecified or what re-assigning firm_id does.

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, no filler. The mutable field list comes first and the state-transition caveat follows, which is the right front-loading for a mutation tool.

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 not be explained, and the destructive/idempotent hints are supplied by annotations. However, for a 7-parameter mutation with zero schema documentation, the description leaves firm_id wholly unexplained and is silent on whether omitted fields are cleared or preserved, which matters given destructiveHint=true.

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 0%, so the description carries the burden of documenting 7 parameters. It names 5 of them (display_name, email, phone, notes, pipeline_stage) but never explains firm_id, which is present in the schema and plausibly re-assigns the client across tenants, nor does it clarify client_id targeting.

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 (update) and resource (client) and enumerates the mutable fields: name, email, phone, notes, pipeline stage. It also distinguishes the operation from the sibling convert_prospect, which is the only path to ACTIVE, so an agent can tell the two apart without opening either 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?

Provides an explicit when-not rule: do not use this to make a client ACTIVE (use convert_prospect), and converted clients cannot be demoted to an earlier stage. It does not cover other alternatives such as update_client_goal, but the critical routing decision is stated.

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