check_accessible_names

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

Annotations already declare readOnlyHint=true and openWorldHint=false, so the safety profile is covered. The description goes further and discloses the exact output shape (one tree line per problem with bounds plus the defect, or "No problems."), which matters because there is no output schema. It does not discuss scoping or auth, but none is plausibly needed for a read-only lint.

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-loads the purpose, then the return format, then the routing hint — a sensible order. The colloquial phrasing ("no name to say for") costs a little precision, but every sentence carries information.

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 the return value; combined with usage routing and a clear target set, an agent has enough to call it correctly. Only minor gaps (e.g. how many problems are returned, whether output is truncated) remain.

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%, so session, window and ignore are already documented in the schema (including that window accepts exact titles, full-match regex, or app=RE). The description adds no parameter-level meaning beyond that, so the 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 (lint) on a specific resource (the accessibility tree) and enumerates what it targets: controls, images not inside a named control, and anything focusable that lacks an accessible name. This distinguishes it cleanly from siblings like check_contrast and check_focus_order without the agent opening any 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?

Gives an explicit when-to-use ("check labels after a change") and names an alternative with its selecting condition ("for colors, use check_contrast"). The routing decision is fully specified rather than left to inference.

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