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

Goes well beyond annotations (which only cover readOnly/idempotent/destructive). It discloses where submissions go (email to owner, chat inbox via form_messages, Pro-plan webhook to Slack/Discord/Zapier/https), that the form posts to the site's own address with no third-party service, and that sensitive fields are rejected. This is unusually rich behavioral context.

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 core action, then delivery behavior, then the safety exclusion, then naming. Dense but every sentence carries information. Slightly long, but not padded.

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?

With no output schema, the description compensates by explaining what is returned (an HTML form to drop in with write_files) and the full downstream lifecycle of submissions. Nothing an agent needs to invoke it correctly is missing.

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 baseline is 3, but the description adds meaning: it explains the field concept ('describe the fields the visitor should fill'), the default form name, and the purpose of webhook_url (Pro-plan secondary delivery). The email_to 'usual choice' guidance is also clarified prose beyond the schema.

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+resource: 'Add or update a contact form on a site.' An agent can immediately distinguish it from siblings like list_forms, remove_form, and form_messages, and the return artifact (an HTML form for write_files) is named.

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 a concrete naming convention ('use the name contact unless the site needs more than one form') and an explicit exclusion (not for passwords or card numbers, which are refused). It implies but does not spell out when to prefer this over list_forms/remove_form, though those are self-evidently different operations.

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