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

Goes well beyond the annotations by disclosing that the call blocks waiting on a human, that a missing wait_for selector errors, and that canvas, frame contents and unloaded content are not extracted. It also explains why readOnlyHint=false despite this being a read: it drives a real browser session and depends on user interaction.

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-loaded with purpose, then precondition, then return shape, then limitations. Every sentence carries distinct information with no padding.

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?

Covers the items an agent cannot infer: the human-in-the-loop requirement, the blocking wait, timeout mismatch advice, and extraction gaps. With an output schema present, it need not spell out return fields, though its brief summary of returns is a bonus.

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 all five parameters are already documented with defaults and constraints. The description's 'Prefer format=text for reading; html preserves markup' largely restates the enum descriptions rather than adding syntax or behavior the schema lacks.

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 ('Read a login-protected page') plus the mechanism ('local browser and human-approved capture'). This is clearly distinguishable from siblings like download_media, list_pages and close_browser, which do not read page content.

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 trigger ('Use for authenticated pages or when normal web reading returns a login screen or empty content') and a concrete precondition workflow ('Tell the user to sign in and click Capture page before calling'). It does not name an alternative tool by name, so it stops just short of a 5.

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

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

Beyond the annotations, it discloses the key side effect (an active capture will fail) and the state that survives (saved login sessions are retained), plus the operational constraint about not closing mid-capture. This is precisely the behavioral context annotations cannot convey, and it does not conflict with destructiveHint=false since no persisted data is destroyed.

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 primary action and followed by the side effect and the guardrail. Every sentence carries distinct information with no redundancy.

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 zero-parameter session-control tool with an output schema and full annotation coverage, the description supplies the trigger, the failure mode, and the persistence behavior. Nothing an agent needs to invoke it correctly is missing.

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?

The tool takes zero parameters, so the baseline is 4 and there is nothing for the description to disambiguate. It correctly implies the operation is unconditional on input.

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 and resource ('Close the browser') and ties it to a user intent ('when the user asks to cancel'), so the action is unambiguous. It does not explicitly distinguish itself from the sibling tools, though none of them offer an overlapping close-session capability, so the gap is minor.

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?

It gives an explicit trigger ('when the user asks to cancel') and an explicit exclusion ('Do not call during capture unless cancellation is intended'), which is exactly the when/when-not guidance an agent needs. No alternative tool competes for this action, so no further routing is required.

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

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

Annotations (readOnlyHint=false, destructiveHint=false, openWorldHint=true) cover the mutation/open-world profile, and the description adds genuinely new context: cookie limitations against JavaScript-generated authorization headers, per-file error reporting, and the 1 MiB preview budget behavior. Does not contradict the write-hint by hiding that files land on disk.

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-loaded with the core action, then limitation, then verification requirement, then the preview branch. Every sentence carries actionable information with no filler.

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?

An output schema exists, so return shapes need not be restated, yet the description still notes the returned fields and error surface. Combined with the auth caveat and sequencing relative to auth_fetch, an agent has everything needed to invoke it 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, but the description adds real meaning to include_preview (returns small PNG/JPEG/WebP to the AI within a budget; larger files require an external viewer) beyond what the schema states. output_dir and urls remain schema-only.

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 (download) and resource (attachments/media) plus the mechanism (saved browser cookies) and scope constraint (only what the task needs). It is clearly distinguishable from siblings like auth_fetch and list_pages.

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 sequencing ('Run after auth_fetch finishes'), a success-verification instruction ('Check downloaded before reporting success'), and a conditional routing rule for include_preview (small images inline vs. larger files needing a local viewer). Covers both when to use and how to branch.

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

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

Annotations already declare readOnlyHint, idempotentHint, and openWorldHint=false, so the safety profile is covered. The description adds genuinely new behavioral context: it does not navigate (no side effects on the pages) and 'does not capture page content', explicitly bounding what the tool will and will not return. That boundary is the kind of detail annotations cannot express.

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 short sentences, zero filler, with the scope constraint ('without navigating') placed first and the output/limitation statement second. 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 zero-parameter, read-only, idempotent list tool with an output schema present, the description covers everything needed to call it correctly: what it enumerates, that it has no navigation side effect, and what data it returns versus omits. Return-value detail is legitimately delegated to the output schema.

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?

The tool takes zero parameters, which is the baseline-4 case per the rubric. There is nothing for the description to clarify, and it correctly describes the output shape (URLs and titles) instead of inventing parameters.

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 (Inspect) and resource (open browser tabs), and the qualifier 'without navigating' narrows the scope precisely. It does not name or differentiate against siblings like close_browser or auth_fetch, but the resource is unambiguous enough that confusion is unlikely.

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?

Usage is implied by the phrase 'open browser tabs' rather than stated: an agent can infer this is the tool for enumerating existing tabs. There is no explicit when-to-use condition, no exclusions, and no reference to the sibling tools that also touch browser state.

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