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

Annotations already declare readOnly, idempotent, non-destructive, and closed-world, so safety is covered. The description adds genuinely new context: 'No network call' (local, instant, no quota) and what the result contains (pixel width, cut-off, truncated preview), which the agent could not infer from annotations alone.

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, zero padding, and the core capability is front-loaded before the usage note. 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?

With no output schema, the description correctly compensates by describing the return content (pixel widths, desktop vs mobile cut-offs, truncated text). The only small gap is that it never notes the description param is optional or whether a title-only check is meaningful.

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% with only two simple string params, so the schema already carries the load. The description restates that the inputs are a title and meta description but adds no format, length, or optionality guidance (e.g. that description is optional). 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?

States a specific verb and resource ('Estimate how a title and meta description show in Google') and enumerates the concrete outputs (pixel width vs desktop/mobile cut-off, truncated text). This clearly distinguishes it from siblings like check_focus_keyword, check_ai_visibility, or validate_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?

Explicitly frames the workflow: 'Use it to iterate on title and description variants until they fit.' That tells the agent when this tool belongs in a loop, though it names no alternative tools or exclusion conditions.

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