a11y_diff

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

With no annotations, the description carries the behavioral burden. It discloses the comparison logic and output categories, and clarifies input formats. However, it does not state whether the operation is read-only, what the exact return structure is, or how errors like invalid JSON or missing files are handled.

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. The main purpose and output categories are front-loaded, followed by input format constraints. Every sentence 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 simple two-parameter tool with no output schema, the description covers the core purpose, input formats, and high-level output categories. It is slightly incomplete regarding the exact return format and prerequisites for obtaining snapshots, but overall it gives an agent enough to invoke the tool correctly.

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 adds meaningful detail beyond the schema by specifying that inline JSON should start with '{' and that file paths are accepted. It also reinforces the before/after ordering implied by the parameter names.

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?

The description states a specific verb ('Compara') and resource ('dos snapshots de accesibilidad'), and details exactly what is compared: added/removed/renamed interactives and focus order changes. This clearly distinguishes it from siblings like a11y_diff_urls, which operate on URLs rather than snapshots.

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?

The description gives a clear usage context: comparing accessibility snapshots before/after a deploy. It also specifies accepted input forms (inline JSON or file paths). It does not explicitly mention alternatives or exclusions, but the context is strong enough for an agent to know when to use it.

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