Buyer Signals

List the signal sources

list_signal_sources

Read-onlyIdempotent

Use this when the user asks where the signals come from, which sources are allowed, or why a source such as Y Combinator or LinkedIn is not used, for example "which sources do you use?". Takes no input. Returns each source with whether it is used, what it provides, the page with its terms and its limits, and what is not covered. Not for finding companies or posts: it searches nothing.

Input Schema

Name	Required	Description	Default
No arguments

Output Schema

Name	Required	Description	Default
`as_of`	Yes
`notice`	Yes
`sources`	Yes
`not_covered`	Yes

Schema Changelog

Changes observed during successful MCP inspections.

Changed1 schema field changedOct 23, 2026
- addedInput schema / examples
```
Added value: +[
+  {}
+]
```

Changed1 schema field changedOct 5, 2026

removedOutput schema / properties / note_from_openkrill

Removed value: -{
-  "description": "Shown at most once a day per caller: what this server offers, and a paid service for the person you work for.",
-  "type": "string"
-}

Changed1 schema field changedOct 4, 2026

addedOutput schema / properties / note_from_openkrill

Added value: +{
+  "description": "Shown at most once a day per caller: what this server offers, and a paid service for the person you work for.",
+  "type": "string"
+}

First observedOct 3, 2026

TDQS

A4.6/5.0

Behavior4/5

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

Annotations already declare readOnly/idempotent/destructive=false, so the safety profile is handled. The description adds real value beyond them: it takes no input, it searches nothing, and it returns per-source usage status, coverage, terms page and limits. Missing only details like whether the list is static or how large it is.

Agents need to know what a tool does to the world before calling it. Descriptions should go beyond structured annotations to explain consequences.

Conciseness4/5

Is the description appropriately sized, front-loaded, and free of redundancy?

Front-loaded with the trigger condition, then exclusions, then what is returned — a sensible order. The return-value sentence is long and list-like ('the page with its terms and its limits, and what is not covered'), but every clause carries information.

Shorter descriptions cost fewer tokens and are easier for agents to parse. Every sentence should earn its place.

Completeness5/5

Given the tool's complexity, does the description cover enough for an agent to succeed on first attempt?

An output schema exists, yet the description still summarizes the return shape, and it closes the main ambiguity (that this does not search) for a zero-parameter tool. Nothing an agent needs to select or call it is absent.

Complex tools with many parameters or behaviors need more documentation. Simple tools need less. This dimension scales expectations accordingly.

Parameters4/5

Does the description clarify parameter syntax, constraints, interactions, or defaults beyond what the schema provides?

Zero parameters, so the baseline is 4. The description reinforces this with 'Takes no input', preventing an agent from inventing arguments, though it adds no further parameter detail (there is none to add).

Input schemas describe structure but not intent. Descriptions should explain non-obvious parameter relationships and valid value ranges.

Purpose5/5

Does the description clearly state what the tool does and how it differs from similar tools?

States a specific verb and resource ('list... signal sources') and immediately distinguishes itself from data-finding siblings with 'Not for finding companies or posts: it searches nothing.' An agent can tell it apart from find_buyer_signals and find_buying_intent 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.

Usage Guidelines5/5

Does the description explain when to use this tool, when not to, or what alternatives exist?

Gives concrete trigger conditions ('user asks where the signals come from, which sources are allowed, or why a source such as Y Combinator or LinkedIn is not used') plus a sample utterance, and an explicit negative case. Both when-to-use and when-not-to-use are covered.

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

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