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

No annotations are provided, so the description carries the full behavioral burden, yet it says nothing about permission needs, whether the update is partial or full-replace, or what is returned. The crucial 'replaces entire object when set / pass null to clear' semantics for metadata exist only in the schema, not here.

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 words with zero waste is technically concise, but the brevity is under-specification rather than economy; there is nothing front-loaded beyond the bare verb+resource.

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?

A 9-parameter mutation tool with no annotations and no output schema needs the description to cover partial-update behavior, the role of project_id/project_slug as a target selector, and resolution behavior. None of that is present; the agent must read the whole schema to infer it.

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% – every one of the 9 parameters including contact_id, project_id/project_slug and the metadata replacement rule is documented inline. The description adds no meaning beyond the schema, so baseline 3 applies.

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?

A specific verb plus resource ('Update a contact') that an agent can trivially separate from get_contact, create_contact and list_contacts by name. It stops short of 5 because it never indicates the scope of the update (which fields, single contact by ID) as the description itself.

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?

There is no guidance on when to use this versus update_company or merge_companies, no prerequisite that a contact_id must first be obtained via list_contacts/get_contact, and no note about what happens to fields omitted from the call.

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