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

Annotations already declare readOnlyHint, idempotentHint, non-destructive and closed-world, so the safety profile is covered. The description's genuinely additive contribution is the negative disclosure that credentials are never returned, which is useful but modest. It adds no information about pagination, caching, or error behavior.

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, front-loaded with the returned-field list and closing with the one important exclusion plus the alternative tool. No filler or redundant restatement of the title.

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 carries the burden of describing return values and does so by enumerating the fields. It also closes the obvious security question by stating credentials are excluded, leaving nothing essential an agent needs before calling it.

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% and the single session_id parameter is fully documented in the schema, including where it comes from (spicrawl_session_create or spicrawl_session_list). 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 and resource ('Return one session's metadata') and enumerates exactly which fields come back (status, engine, proxy/exit, usage count, expiry, lease holder, context summary). It also explicitly differentiates itself from the sibling spicrawl_session_context by naming what that tool is for instead.

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 routes the agent away from this tool when credentials are needed, naming spicrawl_session_context as the alternative. It gives clear context for a read of session metadata but does not state when to prefer spicrawl_session_list versus this tool, so it stops short of full explicit when/when-not guidance.

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