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

Annotations already declare destructiveHint=true and non-idempotent, but the description adds context annotations cannot: sensitive-field refusal behavior and the required fallback to browser_handoff. "Replace" also signals that any existing value is overwritten. It does not discuss retry/reconciliation, though request_id in the schema partly covers 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, no filler, and the operative instruction plus the critical safety exclusion are front-loaded. Every clause earns its place.

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 6-parameter mutation tool with no output schema, the description covers purpose, the sensitive-field refusal path, and the handoff alternative. Return/reconciliation semantics are delegated to the schema's request_id documentation, which is a reasonable division of labor.

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% and all six parameters are documented in-schema (ref pattern, value maxLength, context_id example, request_id retry semantics). The description adds nothing about parameters, so the baseline 3 is appropriate.

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 ("Replace the value of an ordinary text field"), and the word "ordinary" scopes it against siblings like browser_type. It never explicitly contrasts itself with browser_type, so an agent must infer which of the two to pick for a plain text input.

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 explicit exclusions (passwords, one-time codes, payment details), states the consequence (fields are refused) and names the correct alternative (browser_handoff, which the user must use instead). This is a complete when/when-not/alternative triad.

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