列出 pi-web 会话

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

Annotations already declare readOnlyHint=true and openWorldHint=true, so safety is covered. The description adds a genuinely non-obvious behavior: unread uses this MCP's own read cursor and is NOT shared with the browser's unread markers — an agent would otherwise mis-model the state. It does not discuss result ordering guarantees or pagination beyond what `sort`/`limit`/`force` already state in the schema.

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 the two disambiguation rules. For a 10-parameter tool the text is dense but every clause maps to a decision the agent must make; no filler and no restatement of field defaults already in the schema.

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 10-param, no-output-schema tool with only two annotations, the description covers the highest-risk ambiguities (unread cursor, keyword scope, sibling routing). It omits return-shape/ordering description and does not explain `include_subagents` vs `include_empty` intent beyond the schema, which keeps it just short of 5.

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 baseline is 3. The description goes beyond the schema by disambiguating the enum value `unread` (whose cursor semantics the enum name alone hides) and by bounding what `keyword` actually matches. That is real added meaning over the field descriptions.

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?

Opens with a specific verb+resource (列出/筛选 pi-web 里的 pi 会话) and immediately enumerates the filter axes (项目目录、关键词、状态、时间). It explicitly names two siblings it is not — piweb_search_sessions and piweb_triage — so an agent can route without 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?

Provides explicit when-to-use-else guidance: keyword only covers 会话名称/首条消息/目录, so full-text search must go to piweb_search_sessions; '哪些会话在等我' must go to piweb_triage. It also scopes the ambiguous status=unread value. This is a routing rule set, not a hint.

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