session_block

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

Since no annotations are provided, the description must carry behavioral disclosure. It does cover the central behavior and its scope ('Действует на активную вкладку'), but it does not describe persistence, reversibility, or how the block interacts with navigation or session lifecycle.

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?

The description is short and front-loaded with the key operation. The small redundant fragment 'Паттерн request blocking' and a slightly awkward mix of Russian/English keep from being a perfect 5.

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 one-parameter tool with an output schema, the description is reasonably complete: it names the resource, the action, the parameter meaning, and a scope. The only real gap is not specifying the exact pattern syntax or the unblocking path, which would be helpful for an agent.

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 schema only provides an empty 'pattern' string. The description gives it meaning by explaining that the URL must contain the pattern and providing an example ('analytics', '**.gif'). This compensates well for the 0% schema coverage, although exact glob syntax is not formally documented.

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 clearly states what the tool does: 'Заблокировать запросы, URL которых содержит pattern' (block requests with a URL pattern) and positions it as request blocking. This distinguishes it from navigation/reading tools and from the sibling session_unblock, though it does not name that sibling explicitly.

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 clear enough at a high level: block requests matching a pattern on the active tab. However, there is no explicit guidance on when not to use it, no mention that session_unblock undoes this, and no context about when this is preferable to other sibling tools.

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