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

Annotations already declare readOnlyHint, idempotentHint and openWorldHint=false, so safety is covered. The description adds genuinely non-obvious behavior: window=0 returns the full parent section rather than the small indexed block, and truncated=true signals a character-limit cut. It doesn't discuss ordering or size limits, but the important behavioral quirk is disclosed.

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 action, then two labeled sections for when/when-not, then the window=0 caveat. Efficient overall, though the bold emphasis markers and the 'main tool for evidence' positioning sentence are slightly redundant given the surrounding text.

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?

Three optional parameters, an output schema already present, and annotations covering safety — the description supplies exactly the missing pieces (mode selection, window=0 behavior, truncation flag) and need not restate return values.

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; however the description explains the special semantics of window=0 (parent-block return) that the schema's 'expand N chunks' wording does not convey, and frames doc_id/chunk_id as alternative whole-document vs. chunk reads. This is meaningful meaning added on top of the schema.

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?

Description states a specific action pair — fetch surrounding context for a matched chunk, or read a whole document by doc_id — and labels itself the primary evidence-retrieval tool. It is clearly distinguishable from 'search' (existence checks) and 'list_sources' (enumeration).

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?

Contains explicit 何时用 (when the snippet is insufficient / full clause needed) and 何时不用 (just confirming a document exists — search suffices) sections, naming the sibling tool that covers the excluded case. Routing is fully determined.

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 cover read-only, idempotent, and closed-world safety, and the 'once is enough' note largely restates idempotence. The description earns credit beyond that by explaining that `capabilities.retrieval_mode` reports whether semantic retrieval is actually available, warning that `lexical` means synonym rephrasing may fail — a meaningful behavioral caveat the 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?

Front-loads the purpose, then uses labelled sections for when-to-use, when-not-to-use, and the return-value caveat. Every sentence is doing work, though the markdown bolding and multi-section layout make it slightly heavier than the small scope requires.

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 values need no explanation, yet the description still flags the one return field whose meaning affects downstream behaviour (retrieval_mode). For a zero-parameter discovery tool this leaves nothing an agent needs ambiguous.

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. The description still adds a little value by framing what the returned filter metadata is intended to support (department/type/time filtering), but there is no parameter semantics to clarify.

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 (list knowledge bases) and then explicitly enumerates the three things returned: filters' supported fields, value domains, and the instance's retrieval capability. This clearly separates it from the sibling `search`, which does the actual querying.

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' (unsure which libraries exist, or before filtering by department/type/time) and 'when not to use' (you already know what to look for → go straight to `search`), naming the alternative directly. It even caps invocation frequency with 'once is enough'.

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 readOnly/idempotent/closed-world, so safety is covered; the description goes further by explaining that results are citations meant only to judge whether a chunk is worth expanding, that snippets are capped at 300 characters, and that empty or truncated results carry a `CODE: 说明` hint with next steps. It does not, however, describe ranking/scoring behavior or how many hints might appear, leaving modest gaps for a retrieval tool.

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 return shape, then use/don't-use, then edge-case handling, using bold labels as visual anchors. Every line carries distinct information and nothing is repeated.

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 structure need not be re-specified, and the description still adds the crucial framing that snippets are citation previews rather than evidence. Combined with explicit when/when-not routing against both siblings and hint-handling for empty/truncated results, nothing an agent needs to call this 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?

Schema description coverage is 100%, so every parameter — including the RAG_MAX_TOP_K convergence note and the list_sources pointer for doc_type/department — is already documented in the schema. The description adds no parameter-level detail beyond what the schema provides, 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?

The opening line names a specific verb and resource — hybrid retrieval (lexical + semantic) over an enterprise knowledge base returning snippet-level hits — and immediately defines the return unit (chunk_id + ≤300-character snippet + section path). This cleanly separates it from `fetch`, which is explicitly framed as the tool for full document 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?

It states both sides explicitly: use when you need facts, policies, processes, or document原文 as evidence; do not use when the doc_id is known and full content is wanted — go to `fetch` or `resource`. The alternative is named with the exact condition that selects it, so no inference is required.

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