Select several tabs at once

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

Annotations only supply readOnlyHint=false; the description adds meaningful context by disclosing the three selection modes and that the call reports a selection count. It still doesn't say whether selection interacts with the currently active tab or whether existing selections are preserved when adding.

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?

Three short sentences, front-loaded with the purpose before the API-name parenthetical and the analogy. The raw method names add some noise but the analogy sentence earns its place by concretizing the behavior.

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 3-optional-parameter UI-state tool with full schema coverage and no output schema, the description covers purpose, modes, and the returned count. Only the interaction between new and existing selections is left unexplained.

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 the three parameters are already self-documenting; the description only loosely maps the API names to the all/select/clear behaviors. Baseline 3 is appropriate since the schema carries the parameter semantics.

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 ('Multi-select tabs') plus the downstream effect ('batch operations apply to all of them'), and the Ctrl+click analogy makes the model concrete. It doesn't name a sibling such as browser_activate_tab or browser_group_tabs, so the differentiation is implicit rather than explicit.

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 phrase 'so batch operations apply to all of them' implies the use case, and naming addToMultiSelectedTabs / selectAllTabs / clearMultiSelectedTabs hints at the three modes. There is no explicit when-not guidance and no mention of alternative tools for related selection tasks.

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