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

Annotations already declare destructiveHint=true and idempotentHint=true; the description adds genuinely useful context on top by explaining that only supplied fields change and that omitted fields are preserved, plus how clearing works. It does not cover auth requirements or what the response contains, which keeps it below a 5.

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?

Three short, information-dense sentences with no filler; the core behavior (partial update) is front-loaded and the API path is a compact trailing anchor for agents mapping to endpoints.

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 nested-object mutation with no output schema, the definition covers merge semantics, clearing, and where keys come from—enough to call it correctly. It omits any indication of what a successful update returns or how invalid column keys are handled, which is the only real gap.

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 earns more by stating the merge semantics of 'fields' (only passed keys are written) and the null-to-clear convention, neither of which is explicit in the schema. The column-key guidance restates the schema and lead_id is left unaddressed.

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 field values of an existing lead') and immediately clarifies scope with the partial-update parenthetical 'only the fields you pass change', which separates it from myphoner_create_lead and the mark_* tools. The HTTP verb/path tail confirms it is a PATCH-style update.

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 actionable context: keys come from myphoner_list_columns, null clears a field, and existing values are overwritten. It does not state explicit exclusions (e.g. when to prefer mark_lead_winner or move_lead over raw field edits), so it stops short of the when/when-not bar.

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